抗菌谱
参考答案：
抗菌药物的抗菌范围。
—It’s difficult for the villagers to cross the river for market.
—I think a bridge _________ over the river.
A．was built
B．is being built
C．has been built
D．should be built
A．灯泡把电能转化为化学能
B．电动机把机械能转化为电能
C．发电机把机械能转化为电能
D．电暖器把内能转化为机械能
