单项选择题

The work "Their" in line 20 refers to which of the following

A．Elements
B．Monitors
C．Customs
D．Practice
<上一题 目录 下一题>
热门 试题

填空题
It is possible that the virus can jump species, ______ (但是没有理由担心它会感染人类).
填空题
C
相关试题