You can also use the SHIFT key to select a consecutive set of fields - just hold the SHIFT key, click the first field you want to copy and then click on the last field you want to copy (all of the fields in between will be selected).
You can also use CTRL-A to select all of fields in the form.
Just so you know you can also copy and paste fields between different forms, not just within the same form.
This is very similar to how you can select files on Windows.
Hope this helps