`III)`

`17` . Remember to turn off the lamps before leaving as lighting costs us too much money.

`->` Remember to Vinf : nhớ phải làm gì.

`18` . We should not take a bath because a bath uses twice as much water as a shower.

`->` Should (not) Vinf : (không) nên làm gì

`IV)`

`19` . announcement (n) : lời thông báo

`20` . completely (adv) : một cách hoàn chỉnh

`21` . interative (adj) : mang tính tương tác

`22` . conservationists (n) : những nhà bảo tồn

17 Remember to turn off the lamps before leaving as lighting costs us too much money.

18 We should not take a bath because a bath uses twice as much water as a shower.

19 announcement     

20 completely              

21 interactive

22 conservationists