语法填空什么时候用what,when,that,where,who,while,whom,which,答:我想知道他们什么时候放他.(2).(用作关系副词,引导关系从句)当...时 There were times when I didn't know what to do.有些时候我不知道该怎么办才好.(3)连接词 conj..当...时 John got engaged to her when travelling last winter.去年冬天旅行时,约翰与她订了婚.3.that (1)代词 ...