问题描述: Tom is not good at maths.He ____________ study it hard. 1个回答 分类:英语 2014-11-24 问题解答: 我来补答 should 应该 再问: A. can B. is C. have to D. has to 四选一 再答: D 不得不(主语第三人称单数用has to) 展开全文阅读