120-1型货车空气控制阀与120阀相比增加了()功能。
A.常用加速制动
B.常用加速缓解
C.紧急制动
D.减速缓解
参考答案:A
Charles was alone at home, with looking after him.
A.someone
B.anyone
C.not one
D.no one
开展青年志愿者行动的基本原则是什么?