① put litter into the dustbin
② stay up reviewing lessons all the time
③ go to school without breakfast
④ wash hands before meals
⑤ open the window and take a fresh breath as often as possible
A:①④⑤
B:②③④
C:①②⑤
如图所示,为了测量某湖泊两侧A,B间的距离,李宁同学首先选定了与A,B不共线的一点C,然后给出了三种测量方案:(△ABC的角A,B,C所对的边分别记为a,b,c):
①测量A,C,b
②测量a,b,C
③测量A,B,a
则一定能确定A,B间距离的所有方案的个数为( )