They spent as many hours as they could ___their lessons.A.study B. to study C. studying
We all know that learning a skill _________ time and effort.
Man’s understanding of nature is developing ________. It never stays at the same level.
______ you are middle school students, you should learn to how to look after yourselves.
---What do you think of ____ talent show in our school? ---I should say it was ___ great success.
Which sign tells us the way out of a building?