Taking care of children calls for your time, abilities, patience and emotions. _____, it is not a simple thing.

A．On the contrary

B．What's more

C．In conclusion

D．On the other hand

不同化学物质的致畸强度的比较一般用（）

A.活产幼仔平均畸形出现数

B.畸形出现率

C.母体畸胎出现率

D.致畸指数

E.母体/发育毒性比值