下列哪项属于安全性评价第三阶段的试验（）。
A.致突变试验
B.亚慢性毒性试验
C.生殖与发育毒性试验
D.代谢试验
E.致癌试验
参考答案：B, C, D
选择正确的单词。
1. January is the (one / first) month of the year.
2. The weather is (snow / snowy).
3. Today is (rain / rainy).
4. December is the (twelve / twelfth) month of the year.
5. There are three (monthes / months) in summer.
6. The weather is hot and (sunny / snowy).
A．提高周期性变化电压的最大值
B．减小周期性变化电压的周期
C．减小匀强磁场的磁感强度
D．增大D形盒的半径
