If you use a very old brwser such as IE6 you may not see the Submit button. If you start tyoing in teh answer box you should see some numbers showing how many characters you have typed and the total number permitted (eg 220/4000). If you click at a point 1 cm to the right of those numbers you should be clicking on where the hidden Submit button is. You answer should then appear.
Try it
Good luck
If you use IE6 as your browser there is no 'submit' button visible. You may need to change your browser. Or you can click in the space where the button should appear- about 1cm to the right of the keystroke counter that shows something like 234/4000 in bold.