单项选择题

What possibly resulted in the evolution from leafless tree to flat leaves

A．The decrease CO2 in levels.
B．The increase of forests.
C．The drop of temperatures.
D．The change of climates like today.
<上一题 目录 下一题>
热门 试题

填空题
The invisibility cloak can make something invisible by wrapping ______.
填空题
What does it mean by researchers painstakingly tuned the design... (Lines 3—4 Para. 5)
相关试题