单项选择题

What's the passage mainly about

A．The internal structure shows how ancient trees grew.
B．The CO₂ lever exerts impact on the leaves of ancient tress.
C．Analysis of ancient fossils paint picture of the Earth's earliest trees.
D．The ancient trees have no leaves and few branches.

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热门试题

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.

单项选择题

According to the fossil reconstruction, what main parts did a tree comprise

A．It comprised a trunk, vertical ridges and palms.
B．It comprised leaves, ferns and palms.
C．It comprised stumps, branches and palms.
D．It comprised a base, a trunk and a crown.