`I.`

`41.` My brother is interested in playing football in his free time
`->`  be interested in + V-ing: quan tâm/thích thú làm gì)

`42.` It took us two hours to clean the house
`->`   It takes/took + sb + time + to-V: ai đó mất bao lâu để làm gì

`43.` Owing to his sickness, he stayed at home
`->` Owing to + N/V-ing: vì lý do gì. "He was sick" chuyển thành cụm danh từ "his sickness"

`44.` Lan is fond of reading books in her spare time
`->`  be fond of + V-ing: thích làm gì

`45.` I spent 30 minutes finishing the test
`->`  S + spend + time + V-ing: dành thời gian làm gì

Câu `17.`  

`46.` She felt sleepy because the film was boring
`->`  S + V because + clause: giải thích nguyên nhân

`47.` He can't carry the box because of its weight / because of the heavy box

`->` S + V + because of + N /V-ing

`48.` It took him two hours to clean the house for his birthday party

`->`  Chuyển từ cấu trúc "spend time V-ing" sang "It took sb time to-V"

`49.` It is no use reaching the top shelf
`->`  It is no use / It is useless + V-ing: vô ích khi làm gì

`50.` I prefer reading books to watching TV
`->` S + prefer + V-ing + to + V-ing: thích làm việc gì hơn làm việc gì