A. 比值越大就越不安全 B. ED50/LD50 C. ED50/TD50 D. LD50/ED50 E. 比值越大,药物毒性越大
A. 正确 B. 错误
A. thunderstorms,hail,and then rapid clearing B. increasing cloud cover lasting for several days C. lengthy wet weather D. low ceilings with thick cirrus cloud