I’d like to go ________ to help people, ________ when they are in trouble.
As we all know, ______ knowledge comes from _______ practice.
We should prevent pollution ________ happily.
The line is engaged. I can’t _____ now.
It had rained for several days. The clothes had _____ near the fire to dry.
This kind of paper was as soft and light as silk but ______ expensive.