$1.$ We have to use a knife and fork for dinner.

$-$ have to + Vo: phải...

$2.$ What were you and your friends doing at 4 p.m. yesterday afternoon?

$-$ QKTD: Wh_question + was/were + S + V_ing...? (dấu hiệu "at + giờ + thời gian trong quá khứ")

$3.$ When spring comes, many Vietnamese villages prepare for the new festival season.

$-$ When + MDD1, MĐ2...

$4.$ He detests going shopping with his friends.

$-$ detest + V_ing: ghét

$5.$ She drives more carefully than her brother.

$-$ S + V + Adj/ Adv + (er) + than + N