速发性毒作用
参考答案：
是指某些外源化学物在一次接触后的短时间内所引起的即刻毒性作用。
_____ do the students do after-school activities every day ?
For more than one hour.[ ]
A. How often
B. How many
C. How much
D. How long
为防止员工发生偷盗行为应明示贵重物品严禁携至单位。
