1. It will take three days for her to finish this assignment
It takes time for sb to V: cần bao lâu cho ai đó làm gì
2. Desktop computers have been used since 1970s
BĐ thì HTHT: S have/has been P2 (by sb/sth)
3. They have exported that kind of products to many countries
Chuyển từ câu BĐ sang câu chủ động
4. The last time Nick worked on the computer was one year ago
(Ai đó/ sự vật gì/ hiện tượng gì đã không… kể từ lúc…)
The last time + S + Verb(ed/PI) +…+ was + khoảng thời gian + ago
= S + Last + Verb(ed/PI) + khoảng thời gian + ago
= S + have/ has + not + Verb(PII)+…+ for + khoảng thời gian
= It + is + khoảng thời gian + since + S + Verb (ed/ PII)
5. Their parents permit the young children to take this excursion without them
permit sb to V: cấm ai làm gì