Teenagers are warned to be careful when making friends online, because when you can’t see a person, they could be __________.
It ______ six years since they last saw each other.
Look at these clouds. ______.
-- Could you give these books to Mr. Mackintosh? -- Certainly, ______ him about something else in any case, so it won't be any bother.
Lu Xun ______ a lot of novels.
A relative of yours ______ this evening.