林木自然整枝的原因是（ ）。
A．枝条太细了
B．校条太密了
C．光照不足了
D．上方光少了
参考答案：C
He also thinks that _____ English movies isn't a bad way because he can _____ the actors say the words. [ ]
A. watch; watches
B. watching; watch
C. watched; watching
D. watches; to watch
标定AgNO3标准溶液可以使用氯化钠基准物。( )
