Water (freeze) if the temperature falls below zero. If he’s angry, his face always (go) bright red. If you put your money in a saving account, you (get) ten per cent interest. If the microphone isn’t working, you (can/not) hear what he’s saying. If there (be) only a few students, we usually close one of the classes. If a balloon is filled with hot air, it (rise). If water (boil), it changes into steam. The machine stops automatically if something (go) wrong.