空气锤主要由砧座、砧垫、上下砧块、锤杆、工作活塞、上下旋阀、工作缸、压缩活塞、压缩缸连杆、锤体、曲轴、齿轮、大齿轮、飞轮等组成.
参考答案：对
After the class was over, the student apologized _______ the teacher ______ his coming late.
A．/; because
B．/; for
C．to; because
D．to; for
子单分析中，如统计（）的数据，直接在分区里选，施工时间不用选
A.2个月
B.1个月
C.3个月
D.1周
