"The boy is a vegetarian."
Translation:De jongen is vegetariër.
Looks like the only error would be the two dots over the last e. Don't know on my keyboard how I'd be able to do that.
You can also do as I did and simply add the necessary language keyboards. Makes my life so much easier. And as stated I do believe most devices you simply need to hold the letter about 2 seconds and you'll have all possible choices for said letter.
And when you're not on Duolingo, you can use alt+137 (you have to use the left alt and the keypad numbers if I'm not mistaken) on a Windows machine, or press the e for a few seconds and then choose 2 on an Apple.
This link shows the alt codes for various characters: http://fsymbols.com/keyboard/windows/alt-codes/list/