A:was not invited
B:didn’t invite
C:hadn’t been invited
D:haven’t been invited
“稻香花里说丰年,听取蛙声一片”这里蛙的鸣叫属于( )
已知向量a→=2,3,b→=-1,2,若ma→+4b→与a→-2b→共线,则 ( )