1.She (ask) has asked me the same question three times since yesterday. (since , yesterday)
2.Nam (read) was reading when I saw him ( Việc nhìn thấy anh ấy đọc sách : QKD;Hành động đọc xảy ra tiếp diễn trong QK - dùng QK tiếp diễn )
3. Will you be ( be ) free next Sunday morning, Mai? ( TLD - Next Sunday moring - Câu hỏi đảo wil lên đầu )
- No. I will ( visit) our grandmother. ( TLD - V giữ nguyên )
He (work) has worked as a research and development chemist for 10 years, then he retired.
( for, HTHT )