17. They are sweeping the streets. …………………………………………… 18. The mailman had already delivered the mail. …………………………………………… 19. He used to borrow my pen. …………………………………………… 20. He had to finish his work on time. …………………………………………… 21. You needn't do all the homework. …………………………………………… VnDoc. Tải tài liệu, văn bản pháp luật, biểu mẫu miễn phí 22. You ought to tell him early. …………………………………………… 23. They don't use the room very often. …………………………………………… 24. They must widen the road to school this year. ……………………………………………