浆液泵的叶轮一般采用耐腐蚀、耐磨合金钢制作，也有用碳钢外衬橡胶制作。
参考答案：对
It was the first time ______ I ______ here.
A．when; had come
B．that; have been
C．when; came
D．that; had been
下列情况下不属于要约邀请的是( )。
A．招标公告
B．拍卖公告
C．标价出售的商品
D．招股说明书
