Of all the methods they provided, ________ is of any help for solving the math problem.
If you want to sell your product you must _____ it.
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?”