1. 没有明确的延长时间限制,只要在规定时间完成PhD dissertation并答辩通过就能毕业;(当然如果导师不同意的话,你也没办法) 2. Doctoral degree with no time limit is considered to be a temporary one and the student's admission status as a Ph.D. candidate will terminate after completion of this period. There are, however, provisions for extensions beyond that specified date without penalty on the part of the graduate school. The extension must be sought in writing from Graduate School at least four months before end of term.