手动设置combox的选项（key/value）

List<KeyValuePair<string, string>> listItem = new List<KeyValuePair<string, string>>();
listItem.Add(new KeyValuePair<string, string>("苹果", "Apple"));
combox.DisplayMember = "Key";
combox.ValueMember = "Value";
combox.DataSource = listItem;

如果key是int：

List<KeyValuePair<string, int>> listItem = new List<KeyValuePair<string, int>>();
listItem.Add(new KeyValuePair<string, int>("苹果", 1));
combox.DisplayMember = "Key";
combox.ValueMember = "Value";
combox.DataSource = listItem;

参考自： https://blog.csdn.net/kankankankan2222/article/details/8330650