7, She has commenced cooking the soup for half an hour.
8, We have done the test for an hour
9, Jack has planted flowers for three hours.
10, They have built the bridge for two year.
11, Nam has learnt English since 1998.
12, Bang has raised birds since May
13, Van has collected stamps since Sunday
14, Hang has listened to music since 8 o'clock.
15, Mai has commenced making a dress since Saturday
16, He has watering the vegetables since nine.
17, Khanh has played computer games since 2002
18, Kim has commenced doing the test since one o’clock
19, Miss Lien has commenced raising the pets since 2010
20, Minh has sold lottery tickets since June