单项选择题

In the mass extinction 65 million years ago, ______ of all species on earth vanished.

A．two thirds
B．half
C．90%
D．30%
<上一题 目录 下一题>
热门 试题

单项选择题
What distinguishes the end-Permian mass extinction from other similar devastations
A．Change of ocean chemistry.
B．Survival of Miocidaris.
C．Causes.
D．Ecological reorganization.
单项选择题
According to the author, when young families are isolated, ______.
A．old people can easily accept the change
B．people can move from place to place
C．individuals can hardly become innovative
D．economy develops at high speed
相关试题