Students should be encouraged to use _____ Internet as _____ resource.
Children under 12 years of age in that country ______ be under adult supervision when in a public library.
— Who is the girl standing over there ? — Well, if you _____ know, her name is Mabel.
— Isn’t that Ann’s husband over there ? — No, it _____ be him — I’m sure he doesn’t wear glasses.
— What's the matter with Peter?— He was seen crying when he was coming out of the teacher’s office. He ____ by the teacher.
They must have been enjoying themselves there, otherwise they _______ so long.