18. This work has to be finished on time
Động từ khuyết thiếu : S + ĐTKT + be + P2
19. It took two hours to correcting their excercises
S + spend + time/money + V-ing.
It takes/took (sb) + time + to do something
20. She began working in this factory since the begining of this year
S + begin (began) + Ving + thời gian
5 sao + cảm ơn + ctlhn nha