如图圆圈a，b，c分别代表赤道、回归线、极圈，图中箭头为从极地上空看地球自转方向。关于c线的表述不正确的是（　　）

关于浮力，下列说法中正确的是（　　）

不能判定两个直角三角形全等的条件是（　　）

C

     There are many festivals at our school. This month is October. In October there is a sports festival. We have the volleyball game and the basketball game during(在……期间) the festival. On October 15th，there is an English festival. On that day we have an English speech contest(演讲比赛)．On October 19th，we have a school trip. We go to Beijing with the teachers. On the last day of this month，there is a music festival. On that day we can enjoy beautiful music. It's really wonderful. Next month，there is an art festival. Students often display(展示) their pictures on that day.