To copy on a tablet the trick is to use a long (in duration) click or touch which brings up a menu. Choose 'select text' which should bring up two cursors. Move these to select the desired portion of text, then do a copy (which is either another long touch or a visible key atop the screen). This may be slightly different in ipad.
Long click/touch is the android equivalent of a windows mouse right click and usually brings up a useful menu. Not sure how similar ipad is.
If you otg a mouse, the right click becomes 'back'.