根据短文内容和所给的汉语提示，写出短文空白处各单词的正确形式。每空限填一词。

Most of the parents take good care of their __小题1:___(自己的) children. They hope that they can be __小题2:__（健康的）.They can get good __小题3:__（成绩）and have a bright  __小题4:__(将来).But some parents don't care their children's ideas and hobbies. _小题5:___(甚至) they don't give their children a __小题6:___(机会)to have their free time. They don't care what children like to do, __小题7:___(也).All of these make the children __小题8:___(争吵) with the parents. Luckily, my parents can understand me. They always let me make the decision by __小题9:__(我自己). Under the care of my parents, I'm living a comfortable __小题10:___(生活). Here I'd like to send thanks to them.

在TCP/IP 协议簇中， （ ） 属于自上而下的第二层。

A．ICMP

B．SNMP

C．UDP

D．IP