Cars do cause us some health problems, in fact, far more serious ________ than mobile phones do.
Almost all of his time ______ experiments, he has no time to visit his parents.
---Look, our headmaster is over there, playing basketball with some students of our class. --- Oh, he must be ________ to his students.
—Have you seen my dictionary? ---- Is it _______ you bought last week? Perhaps _______ is on your bed.
Your niece is very strict and ______ worth teaching, but your nephew is not. Look, he is now ______ asleep in class.
Our school has used computers in teaching for ten years. As a result, not only______, but students become more interested in their lessons.