问题
单项选择题
Rivets are usually made of（）.
A.wrought-iron
B.aluminum
C.high-tensile steel
D.mild steel
答案
参考答案：D
搜题请搜索小程序“爱下问搜题”
Rivets are usually made of（）.
A.wrought-iron
B.aluminum
C.high-tensile steel
D.mild steel
参考答案：D
