就打叶而言，减少打叶机的钉框距，全使（）增加。
A、大片率
B、叶含梗率
C、梗含叶率
D、碎片率
参考答案：D
黄磷应保存于水中，二硫化碳要用水封贮存。
We are not conscious of the extent of which work provides the psychological satisfaction that can make the difference between a full and empty life.()
A. to which
B. in which
C. at which
D. by which
