题干

在观察了叶片的结构后,晓东将刚摘下的叶片放人70度的热水中,很快发现叶片表面产生许多的小气泡,并且下表皮的气泡比上表皮的气泡多,这种现象说明(  )

A:叶片下表面的光照弱

B:叶片上表面含叶绿体比下表面的多

C:叶片下表面产生的氧气多

D:叶片下表面的气孔多

上一题 下一题 0.0难度 选择题 更新时间:2019-10-26 07:59:24

答案(点此获取答案解析)

D

同类题5

    One terribly cold day, a snowstorm hit our area. Needing firewood, I quickly set out with my best friend, Bruce, to look for a tree to cut down. Cutting down a tree in a snowstorm can be dangerous. ① So to have a friend who could warn me of dangerso was important.
    When I chose a big 23-meter-tall tree and prepared to cut it down, Bruce suddenly warned me, “Don't cut down that tree! It's too close to the power line!” I wasn't sure about it. So I decided to disregard his warning. I couldn't wait to finish the job and go back home. I began cutting down the tree.② When the tree fell, there was no longer any doubt whether my friend was right.
    The tree caught the power line, bringing it to the ground. I considered cutting the tree off the line. After all, electricity can't travel through wood. As I reached out my finger to touch the tree, pain ran up my arm and through my head. I had been shocked!
    After I returned home and told my mother what happened, she quickly called the power company. Workers from the power company soon arrived. One of them asked if I had touched the tree, and when I told him I had, his face turned pale. “You should have been killed,” he said. It was my boots that saved my life.
    ③Within two hours, the workers removed the tree. Soon the snowstorm calmed down——but not my mother. Even though she was glad that I wasn't hurt, my mother was still serious with me. After all(毕竟), I shouldn't have brushed off my friend's warning.