Rewrite the sentences so that they are nearest in meaning to the sentence printed before them 
`45.` The astronauts last orbited the earth two hours ago.
It is two hours since the astronauts last orbited the earth.
(It is + khoảng thời gain + since + S + VQKĐ)
`46.` Tom’s parents advised him to study hard for the final exam.
Tom was advised to study hard for the final exam by his parents.
(Chuyển sang câu bị động)
`47.` He asked his trainer: “Which activity uses lots of calories?”
He asked his trainer which activity used lots of calories.
(Chuyển sang câu gián tiếp, lùi thì)
`48.` Although she was sick, she still went to school.
Despite her sickness, she still went to school.
(Although S + V = Despite + N/Ving)
`49.` Laura painted a picture, and it’s being shown in an exhibition.
The picture which Laura painted is being shown in an exhibition.
(Viết lại câu sử dụng mệnh đề quan hệ)
`50.` Peter drinks too much coffee, that’s why he can’t sleep.
If Peter didn't drink too much coffee, he could sleep.
(Dùng câu điều kiện loại 2 để diễn tả hành động ko có thật ở hiện tại)

45. The astronauts last orbited the earth two hours ago.
`=>` It is two years since the astronauts last orbited the earth.

S+ last+ Vp2+O+ TG.

= It is+ TG+ since+ S+ last.
46. Tom’s parents advised him to study hard for the final exam.
`=>` Tom was advised to study hard for the final exam but his parents.

Ta chuyển thành CBĐ thì QKĐ.
47. He asked his trainer: “Which activity uses lots of calories?”   
`=>` He asked his trainer which activity used lots of calories.             
48. Although she was sick, she still went to school.
`=>` Despite her sickness, she still went to school.

Although= Even though= Though + clause

= Despite + phase N/Ving/ the fact that...
49. Laura painted a picture, and it’s being shown in an exhibition.
`=>` The picture which Laura painted is being shown in an exhibition.

Sử dung MĐQH which:

N(thing)+ which+ V+O.(bổ sung ý nghĩa cho chủ ngữ)

N(thing)+ which+ V+O.(bổ sung ý nghĩa cho tân ngữ)

50. Peter drinks too much coffee, that’s why he can’t sleep.

`=>` If Peter didn't drink too much coffee, he could sleep.

Câu điều kiện loại 2