情态动词must与have to用法 — 英语填空题
题目
用 must, mustn't, have to 或 don't have to 的适当形式填空（每空一词）。We ___ (not need to) take umbrellas today — it's sunny. But we ___ (be told to) return the books to the library before Friday, because that is the school rule. Also, you ___ (绝对不可以) swim in the river alone; it's very dangerous.