III. fill in each blank with a suitable preposition :( with , in , at , on )
18.Mr. Quang are loading the truck____________vegetables.
19.I go to school____________half past six 20____________Sunday. I usually listen to music.
21.There are trees and flowers____________front of the house
18. with
19. at - on
21. in
18.on
19.at-on
20.in