Trung bình mỗi giờ ca nô xuôi dòng được là:
1: 32 =  ( Quãng sông AB)
Trung bình mỗi giờ ca nô đi ngược dòng được là:
1: 48 =  ( Quãng sông AB)
Vì hiệu vận tốc xuôi dòng và ngược dòng bằng hai lần vận tốc dòng nước, nên mỗi giờ cụm bèo trôi được là:
( Quãng sông AB)
Thời gian cụm bèo trôi từ A đến B là:
1:  = 192 (phút)
Đáp số: 192 phút

dùng bất đẳng thức 

Tìm lỗi sai từ những từ (cụm từ) đc in nghiêng:

1. Measles are one of the infectious diseases that children get.

2. Nam looked very angrily because his friends said no words.

3. Neither my classmates nor my teacher are going on vacation this weekend.

4. Last night, Alice took a stomachache, so he had to see the doctor.

5. There are less TV programs for teenagers than there are for adults.

Fill in each gap with one suitable preposition:

1. Would you like a cup of tea, sir? - No, thanks. I am ... duty.

2. Her son almost takes ... her husband. Sometimes I can't distinguish between them.

3. The boy looked ... his dictionary to get the meaning of the word "Luckiness".

4. Are there any interesting programs ... at the moment?

5. The plane is flying ... the storm in order to get out of the rain.

Give the correct form of the words in the bracket:

1. Would you please give me some (inform) about the rain, please?

2. I want to know what the ( deep) of this lake is.

3. Mr. Anderson is my (employ) he has a lot of factories.

4. The knife is (use). I can't cut anything with it.

5. (Mouse) are one of the animals which are harmful to our crops.

6. During his (child) the family used to live in the countryside.

7. On a (type) day, we have to learn 4 hours with different subjects.

Complete the sentences from the suggest words and phrases:

1. Susie/born/England/1995.

2. mother/die early/and/father/try hard/bring up/the four children.

3. She/learn/read/write/at/age/four.

4. When/14/leave school/and go/ China/study.

5. She/work very hard/become/famous/doctor.

Rewrite:

1. Listening to English songs is very interesting to me.

-> I find it ....

2. They are not old enough to drive.

-> They are too ....

3. Nobody in the class plays chess better than Christina.

-> Christina ....

4. They took away his passport so that he wouldn't leave the country.

-> They prevented ....

5. It takes me an hour to do my homework every evening.

-> I spend ....