常用的化学阻垢剂的防垢机理有哪几种？
参考答案：
防垢机理有以下4种：
①分散作用；
②螯合和络合作用；
③絮凝作用；
④晶体变形作用。
Tom: Would you like me to water your plants while you’re on your holiday?
Joe: ________
A．No problem. I was more than glad to do it.
B．I appreciate it, but I’m already finished watering them.
C．Thanks for offering your help, but my brother’s going to do it.
D．Certainly watering plants is my favorite pastime.
检验检疫机构的检验人员到生产企业依法实施检验、鉴定和监督管理时，有关企业应当按照检验检疫机构要求提供交通工具（）。
A、正确
B、错误
