Users practicing this topic

Post date	Users	Rates	Content
2015-06-17	piyo	53	Check this topic
2013-02-27	Lauren	88	Check this topic
2013-02-25	Vanan	100	Check this topic
2013-02-25	Vanan	95	Check this topic
2014-10-28	svt.ntu	85	Check this topic

Topic title: With points from the lecture, explain the formation of collapse sinkhole.

Topic category: TOEFL speaking