填空 1. It is necessary (sit) down to have a rest. 2. If he___ _ (be)to come, what should we say to him? 3. These water cups ____(make) of paper. 4. Their medical team(医疗队) ____(make) up of doctors ,nurses and other skilled members. 5. There would no longer ____(be) lives if there ( be) no water on earth.