在热浸锌前钢材表面除锈应符合设计要求和国家现行有关标准的规定。处理后的钢材表面不应有()、焊疤、灰尘、()、水和()等。
参考答案:焊渣;油污;毛刺
根据句子意思,填入合适的介词。
小题1:You should listen __________ the teacher in class.
小题2:Are you ready __________ the class?
小题3:There are two beautiful pictures __________ the wall.
小题4:Happy Birthday! This is the present _________ you.
小题5:We are having a sports meeting __________ the playground now.
简述演出经纪业务内容。