13c              14a          15b         16a        17b          18b           19c      20b

b2:  1.will be working               2.will build                 3.met            4.go              5.will be spending           6.will/do

7.will be working        8.will visit

b3:

1.despite being young,Quang Hai-footballer plays football beatifully

2.my father used to live in a small village when he was young

3.how far is it from Thanh Hoa to Ha Noi city?

4.i used to walk to school when i was a student

.less electricity will be used in the future

5.public transport will be used when travelling long distance by the students in my school

6.the lights will be turned off by me when leaving thr room or going to bed

7.a great deal of nenergy will be offered by wind power next century

8.sources of energy will be used more effectively for our future

ban tham khao