健康危险度是指外源化学物()
A.损害机体的固有能力
B.损害机体的强度
C.损害机体的可能性的定性估计
D.损害机体的可能性的定量估计
E.不损害机体的可能性
参考答案:D
—I'm a little tired. Let's go to the zoo by taxi.
—We _____ take a taxi. It's not far from here. [ ]
A. can't
B. mustn't
C. couldn't
D. needn't
判断聚合物可模塑性的方法是螺旋流动试验。