Question

какие времена надо поставить в предложениях: The teaching assistent ( explains/explaining)to students how to use the new microscope. What (you/look) at?-The sky.It (look) as if its going to rain.The famous opera singer(apptar) ft opera house tonight.

Answer 1

1. The teaching assistent is explaining to students how to use the new microscope. (Pr. Contin.)
2. What are you looking at? (Pr. Continuous)-The sky.It looks (Pr. Simple) as if its going to rain.
3. The famous opera singer (apptar) ft opera house tonight - Здесь у вас ошибка в написании глагола. Скорее всего, здесь будет is appearing (Pr. Cont)

Answer 2

is explaining- what are you looking at - looks - is + глагол с окончанием ing (вы неправильно вбили написание, поэтому трудно понять что это за глагол)