— You all like your English teacher?

— Yeah, she devotes herself ____ to teaching and it earns her a good reputation. [ ]

A. originally

B. extremely

C. obviously

D. entirely

包过滤防火墙是最简单的防火墙，它作用在（），通常只包括对源和目的的IP地址及端口的检查。

A.物理层和数据链路层

B.网络层和传输层

C.数据链路层和传输层

D.传输层和应用层