It has been said that “happiness is like a butterfly, which, when _ _, is always beyond our grasp but which, if you will sit down quietly, may alight upon you."
Lucy was completely ______ after jogging in the hot sun all afternoon; she had little energy left.
---where have you been? ---I___in the heavy traffic, or I would have been here earlier.
The man insisted that he ___ innocent.
It ______ last night ______ Tom saw an interesting film in Dongfeng Cinema.
Only when class began ______that he had left his book at home.