怎么使用response.write来做一个javascript的alert弹出窗口

Page.RegisterStartupScript("alert", "<script language=javascript>alert('添加成功');</script>");
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response.write("<script language='javascript'>window.open('URl');</script>")
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Response.Write("<script>alert('aaaaaaaa')<script>");
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response.write("<script language='javascript'>alert('message');</script>")

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Response.Write("<script language=javascript>alert('我来晚了!!')</script>");
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C#
Response.Write("<script language='javascript'>alert('我来晚了!!')</script>");