Cola

1 ou 2

a-could came / b-were

c-don't ask / d-could not have gone

e-have / f-were

g-had gone / h-explain

a-They/ to get better grades - if they/ to study more.

they will get better grades if they study more.

they would get better grades if they studied more.

they would have got better grades if they had studied.

b- If he/ not to get up earlier- he/ to arrive late.

if he does not get up earlier he will arrive late.

if he didn't get up earlier he would arrive late.

if he had not got up earlier he would have arrived late.

* a- didn't came / b-will study

c-listens / d-doesn't teach

e-plays / f-saw

g-will be / h-traveled / i-will call