We have ______ up early in order to catch the early bus.
A:used to get
B:been used to get
C:used for getting
D:been used to getting
已知集合A=1,2,3,4,5,B=x,y|x∈A,y∈A,x-y∈A,则B中所含元素的个数为( )
①你要想想办法____让你的文具回家____
②一分钟真重要呀 ____
③听了狗熊的通知____大家为什么没来开会呢____