—Becareful,children!You

问题详情：

—Be careful, children! You ________ step on the grass.

—Sorry. We ________ do that again.

       A. needn’t; won’t        B. mustn’t; won’t       C. can’t; will   D. don’t have to; will

【回答】

B

知识点：虚拟语气与情态动词

题型：选择题