III.
1. A: Have you ever met (Thì HTHT)
B: sat (Thì QKĐ)
2. A: have you started (Mặc dù có ago nhưng How long là của HTHT)
B: have rencently complete (HTHT); asked (QKĐ)
3. A: saw (QKĐ)
B: have already seen (HTHT)
4. A: has worked (for + khoảng thời gian: thì HTHT)
B: started (10 years ago: thì QKĐ)
#chuchoctot!