The answer is the same as when you asked- and were answered- here:
http://talk.qa.collegeconfidential.com/united-kingdom/2132879-do-top-uk-universities-look-at-american-highschool-transcripts.html#latest
and here:
http://talk.qa.collegeconfidential.com/united-kingdom/2132710-what-does-it-take-to-get-into-oxbridge.html#latest