Read the rules and the examples. then make sentences. we use this/these for things near us. we use this in the singular and these in the plutal. we use that/those for things far away from us. we use thar in the singalar and those in the plural

b: then where have you been? (present perfect)

a: oh, nowhere. i wanted (past simple) to go to america two years ago,but now i don't want to go there.

b: why?

a: i understood (past simple) that my wish is impossible, so i abandoned(past simple) that idea. 

и 2-я

b: have you heard some interesting news? (present perfect)

a: no.

b: i heard (past simple) that brian flunked (past simple) his exam last week. 

a: why did (past simple)he flunk the exam?

b: he lost (past simple)his homework, so he didn't repeat a topic.(past simple)