A:when was it that
B:that it was whe
C:where it was that
D:it was where that
①函数f(x)在其定义域上是单调函数.
②f(x)的定义域内存在区间a,b,使得f(x)在a,b上的值域为 a2,b2 .
①娉婷:____。
②鲜妍:____。
③冠冕:____。
④呢喃:____。
下列有关生物膜的叙述,错误的是( )