The students will put off the match until next week, ________ they won't be so busy．
A.whileB.whichC.whenD.then在线课程C
解析：
“they won't be so busy”说的是下周的情况，即they won't be so busy next week，可知next week这个时间名词在后句中作时间状语，填入后引导定语从句。应先根据句中需要连接词排除易错选的D项。