你要用到什么就写什么呗,using无非让你少写点重复代码而已,
你如果不嫌麻烦,using都不要也没关系
System.Windows.Forms.Button b = new System.Windows.Forms.Button();
System.Threading.Thread t = new System.Threading.Thread(new System.Threading.ParameterizedThreadStart(...));
System.Data.SqlClient.SqlConnection Connection =new System.Data.SqlClient.SqlConnection();