SW-220K转向架的空气弹簧垂向刚度(空载时Cz)为()。
A.120N/mm
B.220N/mm
C.320N/mm
D.420N/mm
参考答案:C
The country will no longer be plagued by turmoil .
A.constant change
B.bad weather
C.utter confusion
D.fuel shortages
中动脉的内膜主要由内皮()内弹性膜组成。