—There are five.
A:member
B:members
C:the members
D:the member
Please keep ____(安静)when you are in a library.
某班有一对同卵双胞胎(由同一个受精卵发育成两个胎儿)的兄弟俩,肤色一个较黑,一个比较白.这种变异的类型和产生原因分别是( )
—Less than three times a week.
社会公德涵盖了人与人、人与社会、人与自然的关系,因此在内容上具有( )