充气轮胎的内胎由环形像胶管和（）组成。
A.胎圈
B.气门嘴
C.缓冲层
D.垫带
参考答案：B
最能完整地体现下图所反映历史事件性质的口号是
A．“废除二十一条”
B．“拒绝在和约上签字”
C．“还我青岛”
D．“外争国权，内惩国贼”
It was with great courage _______ the boy told the truth ______ he had stolen the money.
A．that; that
B．which; that
C．when; what
D．which; /
