People ______ drive after drinking alcohol(酒). It's against the law.
A:mustn't
B:needn't
C:couldn't
D:wouldn't
番茄的果实有红色和黄色之分,这属于( )
下列说法正确的是
在物理学中,把 ____叫做功率。它是反映物体的 ____物理量。一人上楼的功率为50瓦,表示的物理意义为 ____。