( )木屋架安装的准备工作：墙顶上木垫块进行防腐处理，清理保险螺栓上的脏物并校直其弯曲，屋架吊装就位。
参考答案：对
— Is this your ____?
— Yes, she's my mom.[ ]
A. dad
B. grandma
C. mother
When doing your history homework on the Civil War by typing in details to Google, a list of related books will ______ .
A．come on
B．come up
C．come down
D．come across
