A-A+
Why researchers put trees in extra carbon diox
问题详情
Why researchers put trees in extra carbon dioxide in the first study？
A．To learn whether trees can still absorb carbon dioxide under extreme conditions.
B．To get more oxygen from these trees.
C．To evaluate the maximum carbon dioxide that trees can absorb.
D．To see the growth rate of these trees.
参考答案
正确答案：D
解析：关键语句：“The trees grew thirty—four percent fasterduring the first three years．However，in time，the trees slowed to about their normal growth rate．The scientists say this is because trees need other nutrients，such as nitrogen．”可以看出是研究生长规律。A，B，C均和本文无关。
