曲柄销与连杆（）头相连，连杆（）头通过十字头销与十字头相连，最后由十字头与活塞杆相连接。
参考答案：大；小
哪种鸟是最小的？
——John always thinks of others instead of himself.
—— So he does. It is _______ of him to want to help others.
A．aggressive
B．conventional
C．evident
D．typical
