Don’t call him at this time tomorrow, because he ________ a meeting with his teachers.
I don’t think ____ possible to master a foreign language without much memory work.
Is ____ necessary to complete the design before National Day?
I hate _______ when young people speak to the elderly in a rude way.
—How long are you staying there?—_________depends.
.______was known to them all that William had broken his promise______ he would give each of them a gift.