only 放在句首且后接状语时(作状语：副词;介词短语;状语从句)，要使用部分倒装------才用一般疑问句语序。
Only yesterday did his father tell him the truth.
Only when his father came back did he go to bed. (从句无需倒装，主句要倒装)
2. He strongly believed in the three principles: nationalism; people’s rights; people’s livelihood.
他主张三民主义：民主、民权、民生。
3. I felt bad the first time I talked to the group.
the first time 用法相当于连词用法，用来引导从句
链接：It’s the first time that 现在完成时 It was the first time that 过去完成时
4. He taught us during the lunch breaks and the evenings when we should have been asleep.(should have done 本应做而未做)
needn’t have done 本不应做而做了 can’t have done 过去不可能做过
