使机车与转向架在纵向上以关节形式连接起来的是（）。
参考答案：牵引杆装置
If only I to my parents advice.
A．listening
B．listen
C．am listening
D．had listened
It is human nature to think back to a golden age ______ one’s country was strong and respected.
A．if
B．when
C．while
D．after
