The first use of atomic weapons was in 1945, and their power __________ increased enormously eversince.
_____ is known to us all _____ Lu Xun is famous for his great works_____ a great writer.
When he left _____ college, he got a job as _____ reporter in a newspaper office.
We _____ a word unless she asks us_____.
It was _____ that I didn’t like to leave my room.
At the meeting, the old man _____ some good advice about bringing down the market price of housing.