语法填空
【小题1】But like so many other things, it is only too much stress______ does you harm.
【小题2】It was through her study of caterpillars   ________ she discovered the truth about their life cycles．
【小题3】Not until he retired from teaching two years ago   ________ he consider having a holiday abroad．
【小题4】________ I wish my work could be settled within a day!
【小题5】She opened it and let out a deep breath． Inside it ________ (be) two sharp knives．
【小题6】A child, if actively ________ (engage) in classroom activities, can be taught many things．