氟通过什么部位进入农作物体内?()
A.果实
B.颈
C.叶
D.根
参考答案:C
“A good child is one who _____ his mistakes,” most parents would say to their children.
A. is admitting B. will admit C. admitted admits
时钟及同步设备作为地铁通信系统的一个部分,在地铁运营过程中为()提供统一的时间标准。
A.工作人员
B.乘客
C.信号系统
D.PIS系统