对于弹簧的夹轨器，弹簧（）满足要求，无裂纹等缺陷。
A、行程
B、长度
C、弹力
D、压缩
参考答案：A
He ______ to swim when he was five. [ ]
A. can
B. could
C. can be able
D. was able
与月经产生没有直接关系的脏腑是
A．肾B．肺C．胆D．脾E．胃
