China’s population is expected to increase to about 1.5 billion in 2040, _____ it will start to decline slowly.
New medicines and instruments ______ every day to extend life.
A red sky in the morning ______ to be a sign of bad weather.
Hundreds of jobs _______ if the factory closes.
“Look! Everything here is under construction.” “What is the small building that ______for?”
He kept a little notebook, in which ______ the names and addresses of his friends.