1 he has had a cold for a week 

-> thì HTHT + for 

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

2 they have bought  the new house since april 

-> thì HTHT + since 

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

3 my family has been here since christmas

-> thì HTHT + since 

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

4 we haven't met each other for 10 years

-> thì HTHT + for 

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

5 mr clak has worked  the bank for a long time

-> thì HTHT + for 

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

$1$. He has had a cold for a week.

`->`for + khoảng thời gian 

$2$ They have bought  the new house since april.

`->`since + quãng thời gian

$3$. My family has been here since christmas.

`->`since + quãng thời gian 

$4$. We haven't met each other for 10 years.

`->`for + khoảng thời gian 

$5$. Mr clak has worked  the bank for a long time.

`->`for + khoảng thời gian