Question

高校生

(1)(2)の答えがそれぞれなぜ①②になるのですか？

[基本問題]
(1) I will go home for the vacation as soon as
1 finish
(2) I have no idea when he (
1 comes
will finish
3 am finishing
finished
) next.
coming
③3 will come
4 has come