3 we have flown to Singapore for 5 years

-> thì HTHT + for 

-> s + have / has + VPII + for + 1 khoảng thời gian

4 i haven't cut my hair since  november 

-> thì HTHT + since 

-.> s + have / has + VPII + since + 1 mốc thời gian

5 we  haven't called each other for 5 months 

-> thì HTHT + for 

-> s + have / has + VPII + for + 1 khoảng thời gian

6 we haven't met for a long time. 

-> thì HTHT + for 

-> s + have / has + VPII + for + 1 khoảng thời gian

7 how long have you had it 

-> thì HTHT 

-> s + have / has + VPII 

8 i have never eaten  such a delicious meal before

-> thì HTHT 

9 the last time I saw him was 8 days ago

-> thì QKĐ 

10 it is four days since I took a bath

-> sau since + thì QKĐ