Sending 2 subject test scores to the schools that recommend 3 scores

<p>I was wondering sending 2 subject test scores would significantly lower my chance of getting in the schools such as Northwestern, and JHU (they recommend 3 subject tests).
i have some solid scores in two subjects (790 in math2 and 750 in UShistory) but cannot think of another subject to take.
does anybody know someone who got into those schools with only 2 subject tests?</p>