1, C – cheap
2, D – group
3, B - pollution
4, A - destruction
5, C – removed
6, B – living in the ocean
7, A – on (to be dependent on: phụ thuộc vào cái gì)
8, B – investigate
9, A – carried
10, D – migrate
11, B – knew
12, A – at (to be at stake: đang nguy cơ, đang bị đe dọa)
13, C – conserve
14, A – shouldn’t
15, D – knew
16, D – into
17, D – pollutants
18, B – would travel
19, C – biodiversity
20, B – destruction
21, A – were
22, A – shouldn’t
23, C – would go
24, D – had
25, C – was repaired
26, B – constant
27, B – biodiversity
28, C – shouldn’t
