People don’t like to work with him because he is lazy

16. People don’t like to work with him because he is lazy.--> If ………………………………………………………………………… *
17. I haven't seen that man here before.--> This is *
18. John started collecting stamps five months ago.--> John has…………………………………………………………………. *
19. Every day I spend two hours learning English-> Every day it takes................................................................................................................. 
20. Hoa is older than Nien.-> Nien is……………………………………………………………………………………………