Ngày 8: Trợ động từ, động từ khuyết thiếu (auxiliary verbs, modal verbs)

Trợ động từ (auxiliary verbs) rất thông dụng, bổ trợ cho động từ chính và thường được sử dụng để nâng điểm ngữ pháp IELTS. Hãy cùng Aland tìm hiểu về trợ đồng từ và động từ khuyết thiếu qua bài học sau đây nhé!

S + auxiliary verb + main verb + O
aux	I S	must aux	study main verb	English. O

Trong tiếng Anh, trợ động từ (auxiliary verbs) thường được dùng để hỗ trợ các động từ chính (main verbs) để hình thành các thì, các dạng, hoặc các thể của câu (nhấn mạnh, phủ định, nghi vấn).

Các loại trợ động từ

Nhóm 1: be, do, have.

Đây là những trợ động từ cơ bản (principal auxiliary verbs), rất thông dụng, rất phổ biến. Ngoài chức năng là trợ động từ, chúng còn có thể làm động từ giới hạn và không cần trợ động từ đi kèm.

e.g. :

	ợ động từ	Động từ giới hạn
	I am studying. (S + be + V-ing)	I am a student. (S + V + O)
	They do not know. (S + do (not) + V)	I did my homework. (S + V + O)
	I have to finish this. (S + have + V_i)	He has a car. (S + V + O)

Nhóm 2: can, could, will, would, shall, should, may, might, must, have (to), ought (to), need (to), needn’t.

Các trợ động từ này còn được gọi là những động từ khuyết thiếu (modal verbs), được kết hợp với các động từ khác để thể hiện sự cần thiết, xác suất xảy ra, ý định, hoặc khả năng.

e.g. : I can speak four languages.

I could give you an honest answer but I should not (do it).

I might talk about it later.

She ought to see the doctor.

I must say that this is a difficult question.

Các dạng thức của động từ và cách kết hợp với trợ động từ

Bare infinitive
(V)

Infinitive
(V_i)

Gerund
(V_g)

Past participle

(V_pII)

walk

study

write

prefer

to do

to walk

to study

to write

to prefer

doing

walking

studying

writing

preferring

done

walked

studied

written

preferred

Các trợ động từ nhóm 1 có thể kết hợp với nhiều dạng thức của động từ để diễn tả những thì, những dạng khác nhau:

be + V_g: thì tiếp diễn
be + V_pII: thể bị động
have + V_i: thể hiện sự cần thiết
have + V_pII: thì hoàn thành
do + V: nhấn mạnh, hoặc đặt câu hỏi

Các động từ khuyết thiếu ở nhóm 2 chỉ kết hợp với dạng thức Infinitive (động từ nguyên thể)

Để diễn đạt khả năng thực hiện hành động của chủ thể

Ta có thể áp dụng cách dùng này đối với trợ động từ can, could trong cả 3 phần của IELTS Speaking cho những câu hỏi cá nhân.

e.g. : IELTS Speaking Part One

Do you prefer cooking at home or eating out?

Honestly speaking, I can’t cook for the life of me, so eating out is the preferred option. However, my mother has been complaining about such ‘lavish, unhealthy’ lifestyle of mine, so I am learning to cook.

Bạn có thể chỉ ra trợ động từ nào cũng được sử dụng trong câu trả lời trên không?

Để diễn đạt xác suất xảy ra sự việc trong tương lai

Ta có thể áp dụng cách dùng này đối với các trợ động từ can, could, may, might, will, would trong cả 3 phần của IELTS Speaking, dạng câu hỏi Problem/Solution (vấn đề, cách giải quyết) của bài IELTS Writing Task Two.

e.g. : IELTS Speaking Part 3

What do you think your country will be like in about 20 years time?

Well, it’s hard to predict because things change so fast sometime, and unexpected things happen. Mmm, I think that given the current rate of development, Vietnam will be a very strong and modern country in quite a short time. At the moment the cities are becoming more and more modern, people are constructing more and more office blocks, and traditional residential areas are disappearing at an alarming rate. Taking all these facts into consideration, I have no doubt that Vietnam will be a safer, cleaner and more beautiful and convenient place to live in the future.

Bạn có thể chỉ ra trợ động từ nào cũng được sử dụng trong câu trả lời trên không?

e.g. : IELTS Writing Task Two – Problem/Solution Essay

Global warming is one of the biggest threats humans face in the 21st Century and sea levels are continuing to rise at alarming rates.

What problems are associated with this and what are some possible solutions.

A possible solution to this problem would be to build flood barriers. Flood defences, such as dikes, dams, and floodgates, could be built along coasts and waterways, thereby stopping the water from reaching populated areas.

Để diễn đạt tính cần thiết, bắt buộc của sự việc

Ta có thể áp dụng cách dùng này đối với các trợ động từ need (to), needn’t, have (to), should, ought (to), must cho những câu hỏi mang tính khách quan trong IELTS Speaking Part Three và IELTS Writing Task Two. Vì những trợ động từ này thường thể hiện sự khẳng định dứt khoát, chắc chắn, chúng ta chỉ nên áp dụng cho những câu hỏi ý kiến khách quan.

e.g.: IELTS Writing Task 2

Which is more important in a child’s school education: academic subjects, learning teamwork through sporting activities, or learning about art and drama?

Generally, academic subjects are the most important part of a child’s education. Children need to have a sound academic basis in order to progress successfully onto further education and establish a career in the future, for this is what society requires.

IELTS Reading Passage 1

HELIUM’S FUTURE UP IN THE AIR

In recent years we have all been exposed to dire media reports concerning the impending demise of global coal and oil reserves, but the depletion of another key nonrenewable resource continues without receiving much press at all. Helium – an inert, odourless, monatomic element known to lay people as the substance that makes balloons float and voices squeak when inhaled – could be gone from this planet within a generation.

Helium itself is not rare; there is actually a plentiful supply of it in the cosmos. In fact, 24 per cent of our galaxy’s elemental mass consists of helium, which makes it the second most abundant element in our universe. Because of its lightness, however, most helium vanished from our own planet many years ago. Consequently, only a miniscule proportion – 0.00052%, to be exact – remains in earth’s atmosphere. Helium is the byproduct of millennia of radioactive decay from the elements thorium and uranium. The helium is mostly trapped in subterranean natural gas bunkers and commercially extracted through a method known as fractional distillation.

The loss of helium on Earth would affect society greatly. Defying the perception of it as a novelty substance for parties and gimmicks, the element actually has many vital applications in society. Probably the most well-known commercial usage is in airships and blimps (non-flammable helium replaced hydrogen as the lifting gas du jour after the Hindenburg catastrophe in 1932, during which an airship burst into flames and crashed to the ground killing some passengers and crew). But helium is also instrumental in deep-sea diving, where it is blended with nitrogen to mitigate the dangers of inhaling ordinary air under high pressure; as a cleaning agent for rocket engines; and, in its most prevalent use, as a coolant for superconducting magnets in hospital MRI (magnetic resonance imaging) scanners.

The possibility of losing helium forever poses the threat of a real crisis because its unique qualities are extraordinarily difficult, if not impossible to duplicate (certainly, no biosynthetic ersatz product is close to approaching the point of feasibility for helium, even as similar developments continue apace for oil and coal). Helium is even cheerfully derided as a “loner” element since it does not adhere to other molecules like its cousin, hydrogen. According to Dr. Lee Sobotka, helium is the “most noble of gases, meaning it’s very stable and non-reactive for the most part … it has a closed electronic configuration, a very tightly bound atom. It is this coveting of its own electrons that prevents combination with other elements’. Another important attribute is helium’s unique boiling point, which is lower than that for any other element. The worsening global shortage could render millions of dollars of high-value, life-saving equipment totally useless. The dwindling supplies have already resulted in the postponement of research and development projects in physics laboratories and manufacturing plants around the world. There is an enormous supply and demand imbalance partly brought about by the expansion of high-tech manufacturing in Asia.

The source of the problem is the Helium Privatisation Act (HPA), an American law passed in 1996 that requires the U.S. National Helium Reserve to liquidate its helium assets by 2015 regardless of the market price. Although intended to settle the original cost of the reserve by a U.S. Congress ignorant of its ramifications, the result of this fire sale is that global helium prices are so artificially deflated that few can be bothered recycling the substance or using it judiciously. Deflated values also mean that natural gas extractors see no reason to capture helium. Much is lost in the process of extraction. As Sobotka notes: "[t]he government had the good vision to store helium, and the question now is: Will the corporations have the vision to capture it when extracting natural gas, and consumers the wisdom to recycle? This takes long-term vision because present market forces are not sufficient to compel prudent practice”. For Nobel-prize laureate Robert Richardson, the U.S. government must be prevailed upon to repeal its privatisation policy as the country supplies over 80 per cent of global helium, mostly from the National Helium Reserve. For Richardson, a twenty- to fifty-fold increase in prices would provide incentives to recycle.

A number of steps need to be taken in order to avert a costly predicament in the coming decades. Firstly, all existing supplies of helium ought to be conserved and released only by permit, with medical uses receiving precedence over other commercial or recreational demands. Secondly, conservation should be obligatory and enforced by a regulatory agency. At the moment some users, such as hospitals, tend to recycle diligently while others, such as NASA, squander massive amounts of helium. Lastly, research into alternatives to helium must begin in earnest.

Questions 1–5

Reading Passage 1 has six paragraphs, A–F.

Which paragraph contains the following information?

Write the correct letter, A–F, in boxes 1–5 on your answer sheet.

a use for helium which makes an activity safer
the possibility of creating an alternative to helium
a term which describes the process of how helium is taken out of the ground
a reason why users of helium do not make efforts to conserve it
a contrast between helium’s chemical properties and how non-scientists think about it

Questions 6–9

Do the following statements agree with the claims of the writer in Reading Passage 98?

In boxes 6–9 on your answer sheet, write

YES if the statement agrees with the claims of the writer

NO if the statement contradicts the claims of the writer

NOT GIVEN if it is impossible to say what the writer thinks about this

Helium chooses to be on its own.
Helium is a very cold substance.
High-tech industries in Asia use more helium than laboratories and manufacturers in other parts of the world.
The US Congress understood the possible consequences of the HPA.

Questions 10–14

Complete the summary below.

Choose NO MORE THAN TWO WORDS from the passage for each answer.

Write your answers in boxes 10–14 on your answer sheet.

Sobotka argues that big business and users of helium need to help look after helium stocks because 10. ……………….. will not be encouraged through buying and selling alone. Richardson believes that the 11. ……………….. needs to be withdrawn, as the U.S. provides most of the world’s helium. He argues that higher costs would mean people have 12. ……………….. to use the resource many times over.

People should need a 13. ……………….. to access helium that we still have. Furthermore, a 14. ……………….. should ensure that helium is used carefully.

YES
NOT GIVEN
NOT GIVEN
NO

prudent practice
privatization policy
incentives
permit
regulatory agency

Đây là một số từ vựng học thuật trong bài tập Reading mà chúng ta có thể sử dụng trong IELTS Speaking và Writing.

*demise* (n)	sự biến mất, sự suy tàn
*depletion* (n)	sự làm suy kiệt
*instrumental* (in) (adj)	quan trọng trong việc…
*mitigate* (v)	giảm nhẹ
*prevalent* (adj)	thịnh hành, phổ biến
*feasibility* (n)	tính khả thi
*apace* (adv)	một cách nhanh chóng
*adhere* (to) (v)	tuân thủ theo…
*dwindling* (adj)	đang giảm dần
*deflate* (v)	giảm phát
*incentive* (n)	sự khuyến khích, động cơ thúc đẩy
*avert* (v)	phòng tránh, ngăn chặn
*predicament* (n)	tình thế khó khăn
*recreational* (adj)	giải trí, tiêu khiển
*obligatory* (adj)	bắt buộc
*diligent* (adj)	chăm chỉ, cần mẫn
*squander* (v)	lãng phí
*alternative* (n, adj)	phương án thay thế
(to) begin in earnest	bắt đầu một cách nghiêm túc

Các bài học trong 30 ngày xây gốc sẽ tập trung vào 6 thì, các dạng động danh tính, trợ động từ, mạo từ, cấu trúc câu bị động, câu điều kiện ...Cả nhà cùng theo dõi để luyện tập tốt nhé.