47. we can see at night

- Clause + so + clause: Vì thế

- Need to V: Cần làm gì

- Can V - inf: Có thể làm gì

48. You shouldn't go diving along because it's quite dangerous

- It's not a good idea + to V: Ý tưởng không tốt khi làm gì

- = S + shouldn't + V - inf: Không nên làm gì

- Clause + because + clause: Vì

49. You need to drink plenty of water when you're out in the sun all day

- It's neccessary for sb to do sth: Cần thiết cho ai làm gì

- = S + need + to V: Cần làm gì

- Clause + when + Clause: Khi

50. You should have a guidebook before you visit a city

47. We need to bring flashlights so we can see at night.

Clause + so + clause: vì vậy 

can + V1: có thể 

48. You shouldn't go diving along because it's quiet dangerous.

shouldn't + V1: không nên làm gì 

49. You need to drink plenty of water when you're out in the sun all day.

need + to V / N : cần 

50. You should have a guidebook before you visit a city.

should + V1: nên làm gì 

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