鸟类有发达的肺，还有一个鸟类特有的、能够协助肺完成呼吸作用的结构是[ ]
A．气管
B．气囊
C．支气管
D．气门
B
I looked for my pet dog ______, but I can't find it ______. [ ]
A. anywhere; somewhere
B. somewhere; anywhere
C. anywhere; everywhere
D. everywhere; anywhere
“和”用于人体表示（）。
A.答应、允许
B.暖和、温暖
C.和睦、融洽
D.身体健康舒适
