轴箱拉杆橡胶圈失效，会使轮对发生非正常位移，出现制动器（）现象。
参考答案：自动上闸
一个三角形中至少有（ ）个锐角。
It is _____ for her to finish that maths problem in such a short time, because she is so clever.[ ]
A. probable
B. impossible
C. likely
D. possible
