--Listen! Is Tom singing in the room? -- No, it ______ be Tom. He has gone to Paris. A. mustn’t B. needn’t C. can’t
—Shall we stop for lunch _______ shall we drive on? —Let’s stop for lunch, but the driver can’t drink _______ drive.
Guilin is ___ attractive city. It’s ____ nice place that many tourists go there every year.
_______, when Marx was already _______, he found it was important to study the situation in Russia, so he began to learn Russian.
---Where is Linda? I can’t find her anywhere. ---She ______ the flowers in the garden.
If we ______ take environmental problems seriously, the earth _______ worse and worse.