You can get a flat and toned abdomen with these exercises. The dead bug is a "perfect exercise for working the deep muscles of our body" The one arm toe touch crunch is an exercise to work the obliques and the rectus abdominis.
The plank is a good way to work your abs without hurting your back. You can also do Russian twists to strengthen the oblique muscles and show off your flat stomach. The one foot toe crunch is a great way to burn fat and tone your body.