There are fifty p____ in my class.
________that the way people spend their Spring Festival has changed a lot in the past ten years.
细胞代谢需要酶的催化,酶的化学本质和催化作用的本质分别是
其中符合图象描述的说法有( )
厨房里发生的下列变化中,属于物理变化的是( )