问题描述：
被动语态的助动词?
情态动词、助动词的被动语态
我书上写
seem to
appear to
happen to
have to +be done
used to
be used to
seem ,appear ,happen ,used ,be used 也是助动词?
情态动词、助动词的被动语态
我书上写
seem to
appear to
happen to
have to +be done
used to
be used to
seem ,appear ,happen ,used ,be used 也是助动词?
问题解答：
我来补答展开全文阅读