Student reaction at Central Oregon Community College is mixed to the news of a part time instructor being arrested and charged with sexual assault.   The college has replaced Thomas Bray, 37, as a part time anatomy instructor. Bray faces several charges after he met a 23-year old woman on line, then the two went back to his residence over the weekend where the alleged sexual assault took place. A college spokesman says background checks are not run on part time instructors. About half of the students we talked to think that background checks should conducted. A few students say the young woman should not have gone back to Bray's residence. He has been placed on paid administrative leave.