A group of middle school students spent two weeks ____the jungle.

(2013·高考江苏卷)Generally，students’ inner motivation with high expectations from others________essential to their development.

There must be ________ with the computer.

His expression suggested that he _______ ill, so theteacher suggested that he _______ sent to hospital at once.

－Excuse me, does Mr Smith’s son live here－He _________ be here, but he has moved.