3、rnin/handin上交deadline最后期限due到期extension延期paper论文/essay小论文termpaper学期报告thesis毕业论文proposal开题报告课程takethecourse选课dropthecourse退课register注册signupforthecourse选课cancel取消selectivecourse/electivecourse/optionalcourse选修课requiredcourse/compulsory必修课lecture讲座 seminar讨论班 credit学分 i