put the following sentences in correct tenses
18. at the moment, he ..................(lie) on the chair and .............................(watch) TV
19. Mr. Tuan ...............................(build) this house in 2009
20. they ..................................(hold) the festival 3 days ago
21. we......................................(not do) our homework now
22. my brother and i ...............................(wait) for a bus at present
23. my mother .....................................(tie) her hair in the bedroom now
24. my friends .....................................(visit) Ho Chi Minh's Mausoleum three weeks ago
25. my sisters ...................................(be) at home yesterday
26. this teacher usually ..................................(read) newspapers when she has free time
27. my mother .................................(teach) my sister how to cook some favourite dishes now
18. is lying-watching
19. built
20. held
21. are not doing
22. are waiting
23. is tying
24.visited
25. were
26.reads
27.is teaching