C# 执行插入语句出错，请各位大神帮忙看看怎么修改

string sql = "inesrt into UserSInfo (UserNum,UserName,UserSex,UserAge,College,Class,Gra,Tel,Remark) values ('" + textBox1.Text.Trim() + "','" + textBox2.Text.Trim() + "','男','" + textBox2.Text.Trim() + "','" + textBox3.Text.Trim() + "','" + textBox4.Text.Trim() + "','" + comboBox1.Text+ "','" + textBox5.Text.Trim() + "','" + textBox6.Text.Trim() + "')";

把insert语句放到sql server 中，并把变量数据如textBox1.Text.Trim()替换成固定字符串然后执行看报什么错