A:4层
B:6层
C:8层
D:10层
水土流失是我国洪涝灾害频发的元凶,水土流失导致江河湖库淤积,加剧洪涝灾害,对我国防洪安全构成巨大威胁。之所以称水土流失是我国洪涝灾害频发的元凶,是因为( )
阅读对话,判断正误,对的写“正确”错的写“错误”
Mingming: What are you doing, Lingling?
Lingling: I'm training. I'm going to do the high jump. What are you going to do for Sports Day?
Mingming: I'm going to run the 100 metres.
如图,直线c与直线a、b相交,且a∥b,则下列结论:①∠1=∠2;②∠1=∠3;③∠3=∠2中,正确的个数为( )