（） is the breakdown of surface tension between oil droplets in an oil water mixture which causes them to join and increase in size. ["Wear","Contaminating","Coalescence","Coarse separating"]
港台馈赠有哪些禁忌？
双动拉伸模上的外滑块、内滑块各起什么作用？
零件在弯曲前，坯料的准备工作应注意些什么？
应收账款的信用成本是指企业持有一定应收账款所付出的代价，包括（） ["机会成本","管理成本","短缺成本","转换成本"]
简述尺蠖鱼蛭病的流行情况。
