我已经尝试过了在VS2010中

i have tried it in VS2010

MessageBox.Show("first line" & vbCrLf & "second line")

在字符串中，只需使用\ r \ n在两行之间添加空白行即可.
或者，只需在下一行使用\ n.

In the string, just use \r\n for add a blank row between the two lines.
Alternatively, just use \n for the next line.

Dim answer as DialogResult

answer = MessageBox.Show("This will make you exit from system.. \r\nContinue??","Exiting system", MessageBoxButtons.YesNo, MessageBoxIcon. Question)

if (answer == DialogResult.Yes) then
 'Do something

end if

默认情况下，我是c#开发人员，因此如果使用此语法无法正常工作，则应该采取措辞，但这应该为您指明正确的方向.

I am a c# developer by default, so appologies if this doesn''t work in this syntax, but this should point you in the right direction.