Dim db as adodb.connection Dim rs as adodb.recordset Dim mitem as listitem Set db = new adodb.connection Set rs = new adodb.recordset With db .provider=”sqloledb” .open “datasource=lab2; uid=sa;pwd=;initial catalog=northwind;” End with rs.open “select productname from products”, db,adopenstatic,adlockoptimistic Do until re.eof Set mitem=lvwproducts.listitems.add() mitem.text=rs!productname rs.movenext Loop lvwproducts是列表视图控件，上述代码不能正确运行，原因不可能是（选择一项）
a)	没有添加columnheaders
b)	Lvwproducts的listitems没有清空
c)	mitem.text=rs!productname错误，应该为mitem.text=rs.fields(“productname”).value
d)	listitem对象mitem没有用new关键字动态生成

a b c d