2m/s = 7,2 km/h
1h30'=1,5h
Vận tốc khi thuyền xuôi dòng là:
v1=18 + 7,2 =25,2 (km/h)
Thời gian thuyền đi xuôi dòng ( A -> B )
t1 = sAB / 25,2 (h)
Vận tốc thuyền đi ngược dòng là:
v2 = 18 - 7,2 =10,8 (km/h)
Thời gian thuyền đi ngược dòng ( B -> A)
t2 = sAB / 10,8 (h)
t1 + t2 =1,5
=> sAB / 25,2 + sAB / 10,8 = 1,5
Giải phương trình trên ta được
sAB = 11,34 (km)

Complete the sentences, using the correct forms or tenses of the verbs in brackets :

1. The telephone (ring).....................while Lan (read)........................book.

2. The woman (sit)...................... besides Lan is Miss Lien

3. Do you mind if I (listen)......................to music?

1. It’s very ________in the summer.

2. John is fromGreat Britain. He __________English.

3. Now I am _____________ my friends.

1.Will they come ( thay / come ) tomorrow ?

2. When will you get ( you / get ) back ?

3. If you lose your iob , what will you do ( you / do ) ?

4. In your opinion , will she ( she / be ) a good teacher ?

5. What time will she sunset ( the sun / set ) today ?

6. Will she get ( she / get ) the job , do you think ?

7. Will david be ( David / be ) at home this evening ?

8. What will the weather like ( the weather / be ) like tomorrow ?

9. There's someone at the door , will you get ( you / get ) it ?

10. How will he get ( he / get ) here ?

1.your/What/doing/mother/is/?

What is your mother doing ?

2.cooking/is/kitchen/she/in/the.

She is cooking in the kitchen .

3.doing/are/What/you/?

What are you doing ?

4.cleaning/the/floor/I/am.

I am cleaning the floor .

5.your/doing/What/is/brother/?

What is your brother doing ?

6.reading/a/book/he/is/new.

He is reading a new book .

1. Tuan and his brother ( not watch ) aren't watching TV at the moment . They ( be ) are asleep .

2. My father always ( come ) comes home late . He ( finish ) finisher work at 5 o'clock .

3. I ( not understand ) don't understand this sentense . What does this work ( mean ) mean?

4. Right now I ( look ) am looking around the classroom . Minh ( write ) is writing in his book .

5. Lien's friend (have ) has a new bike but he ( not like ) doesn't like it very much .

6. Where are your ( do ) doing now ? - I ( unload ) am unloading the vegetables .

7. Where are your children (be ) are ? - They're upstairs. They ( play ) are playing video games.

8. Is Nam ( work ) working in the garden at the moment ?

WRITE THE QUEIONS :

1. She is a nurse .

.......................................................................................

2. She kives with my family in Ha Noi .

->..........................................................................................

3. Tom stayed at home last nigh

->...............................................................................

4. I felt a lot better after the dentist fixed my tooth

->..............................................................................

5. He started this job 2 years old

->.......................................................................