心脏的血液供应主要来自于（） A.左冠状动脉 B.右冠状动脉 C.冠状动脉

— What happened to your brother?

— He slipped on the icy road        after a bus, and had his leg broken. [ ]

A. to chase      

B. chased        

C. chasing        

D. having chased

互相垂直且相交的两条直线肯定在同一个平面上．______．（判断对错）

修复体边缘一般位于龈沟内

A．0.5mm
B．1.0mm
C．1.5mm
D．2.0mm
E．3.0mm

A rescuer can most easily determine whether or not an adult victim has a pulse by checking the pulse at the（）.

A.carotid artery in the neck

B.femoral artery in the groin

C.brachial artery in the arm

D.radial artery in the wrist

活塞在气缸中做往复直线运动进行气体的膨胀。