机床齿轮、轴、汽车半轴，常选用（）。
A.40Cr
B.45
C.35CrMoAl
参考答案：A
侵袭性葡萄胎及绒癌 * * 转移常见部位为______，表现为______，破溃后可出现______。
Everyone in the classroom now.[ ]
A. are
B. has
C. is
D. have
