1 It's over 3 months since tom last had his hair cut
-> sau since + thì QKĐ
2 it's 2 years since my father last came to HN
-> thì HTHT
-> it 's + thời gian + since + thì QKĐ
3 It’s years since I enjoyed myself so much
-> thì HTHT
-> it 's + thời gian + since + thì QKĐ
4 It's two years since I last ate this kind of food.
-> thì HTHT
-> it 's + thời gian + since + thì QKĐ
5 it's hours since mary rang
-> thì HTHT
-> it 's + thời gian + since + thì QKĐ
6 it's 4 years since we last saw him
-> thì HTHT
-> it 's + thời gian + since + thì QKĐ
7 i haven't seen them for years