a) Van toc cua tau khi tau xuoi dong la v1 = a + b (km/h) 

b) Van toc cua tau khi tau nguoc dong la v2 = a - b (km/h) 

c) 
a ____________' 
b _______[--------]-a - b 


a + b ____________[_______]

harvest
country
agree
famous

agree: âm 1 còn lại âm 2

Chọn C

Đáp án : agree 

Vì : agree là âm 1 còn lại trọng âm đánh vào âm 2 

-> C 

a)the missing number is 41

b)the missing number is 31

1. Checking the stock is Tim’s responsibility (chỗ này cần 1 danh từ) . Should any item be missing, he’ll

have to account for it.  RESPONSIBLE

2. The envelop was incorrectly (chỗ này cần 1 trạng từ) addressed, so the letter could not be delivered to Jim. CORRECT

3. Will you please give us some further (cần tính từ ở dạng so sánh hơn) explanation?   FAR

4. Are there any similarities (cần danh từ số nhiều) between them? SIMILAR

5. According to the timetable (cần danh từ), the French lesson starts at 10 a.m. TIME

6. Traveling to the countryside is becoming increasingly (cần trạng từ) popular nowadays.  INCREASE

7. The police are looking for a dangerous criminal (cần danh từ chỉ người) .   CRIME

8. It is illegal (cần 1 tính từ) to own a gun without a special license.   LEGAL

9. Sam phoned to say he would possibly (cần 1 trạng từ) be late home.  POSSIBILITY

10. Japan was very rapidly industrialized (cần 1 động từ ở dạng bị động/tính từ) in the late nineteenth century.   INDUSTRY

ngoài ra những câu này đều phải dựa vào ngữ cảnh và nghĩa của câu để chọn từ nhé

1 . People

2 . Flowers

3. Books

5. The children's blocks

13. False

14. False

15.True

1 people

2 flowers

3book

5 the chidre'sblocks

13 false

14 false

15 true

1 people

2 flowers

3 books

13 false

14 false

15 true

5 ko có tranh nên ko biêts

1. up

2. out

3. for

4. off

5. In

6. for 

7. of

8. out 

9.  out

10. in

A.    Supply the missing prepositions or particles.

I turned__up_at the meeting but the others didn’t come.

My shoes have been worn_out__very quickly since I started walking to the office.

The ship was bound__for_Japan when it ran into a typhoon.

The gun went __off_in his hand while he was cleaning it.

It always pays to buy high-quality goods.__in_the long run it’s cheaper.

There is no cure_for__baldness except a wig.

You will be deprived__of_all privileges.

Plants give__off_oxygen.

I can’t make_over__his writing.

She can always tell pearls_in__real ones. 

A.    Supply the missing prepositions or particles.=> Cung cấp các giới từ hoặc tiểu từ còn thiếu

I turned___at the meeting but the others didn’t come.

My shoes have been worn___very quickly since I started walking to the office.

The ship was bound___Japan when it ran into a typhoon.

The gun went ___in his hand while he was cleaning it.

It always pays to buy high-quality goods.___the long run it’s cheaper.

There is no cure___baldness except a wig.

You will be deprived___all privileges.

Plants give___oxygen.

I can’t make___his writing.

She can always tell pearls___real ones.

Chọn đáp án C

50000 tấn = 50000000 kg.

Lực hấp dẫn giữa hai tàu là:

Đáp án C

50000 tấn = 50000000 kg.

Lực hấp dẫn giữa hai tàu là 

F h d = G . m 1 . m 2 r 2 = 6 , 67.10 − 11 .5.10 7 .5.10 7 1000 2 = 0 , 167 N