EXERCISE 1:
//fastlearn.edu.vn/wp-content/uploads/2019/04/expressup-progress3-gap-fill-read-environment.mp3
EXERCISE 2:
//fastlearn.edu.vn/wp-content/uploads/2019/04/expressup-6.1011-gap-form-filling-assignment-on-global-warming.mp3
//fastlearn.edu.vn/wp-content/uploads/2019/04/expressup-6.11-gap-form-filling-assignment-on-global-warming.mp3
EXERCISE 3:
//fastlearn.edu.vn/wp-content/uploads/2019/04/chinese-6-tests-63-environment-recycling.mp3
265, 359
EXERCISE 4:
//fastlearn.edu.vn/wp-content/uploads/2019/04/expressinter-66-gap-fill-environment.mp3
267, 358
EXERCISE 5:
//fastlearn.edu.vn/wp-content/uploads/2019/04/chinese-6-tests-14-environment.mp3
268, 362
EXERCISE 6:
//fastlearn.edu.vn/wp-content/uploads/2019/04/achieve2-319-matching-environment.mp3
269, 361