“三凹征”是指（）、（）和肋间隙凹陷。
参考答案：胸骨上窝；锁骨上窝
When I said someone broke the school regulations, I ______ you. Why did you get that angry?
A．don’t refer to
B．haven’t referred to
C．wasn’t referring to
D．hadn’t referred to
热机是把______能转化为______能的机器；在热机里，用来做______的那部分能量，与燃料______放出的能量之比，叫做热机效率．
