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

You are tired. You _____ go to bed early.

—Listen! Is that Millie singing?—No. It _____ be Millie. She has gone to Beijing.

—Look at the picture on the wall. It ________be David’s.—Yes, his name is on the first page.

The warm-hearted neighbor      take care of the little girl when her parents were on business, and they appreciated it very much.