young students should not be allowed to work at night,because they( )to sleep Amust Bshould Cneed
问题描述：
young students should not be allowed to work at night,because they( )to sleep Amust Bshould Cneed
答
只能是C ( 只有need 有 need to do 的用法)
其它两个没有 must to do,should to do的用法