It’s quite warm here; we __________turn the heating on yet.

Some aspects of a pilot’s job__________ be boring, and pilots often ________ work at inconvenient hours．

The boy        be very naughty, but he is very lovely.

—Is that boy Alan?—No, it ______ be him. He left for Beijing yesterday.

--- He worked out such different questions at a very young age.--- Oh, he ______ a very smart student then.