______ a language family is a group of languages with a common origin and similar vocabulary, grammar, and sound system.

A．What linguists call

B．It is called by linguists

C．Linguists call it

D．What do linguists call

小刚用同一把尺先后测得一铅笔的长度，并分别记录为18.41cm、18.40cm、18.52cm、18.42cm，其中有一组数据读数或记录错误，错误的数据是（　　）

A．18.41cm

B．18.40cm

C．18.52cm

D．18.42cm