观察下列各式:,,,……请你将发现的规律用含自然数n(n≥1)的等式表示出来__________________. 答案:【答案】【解析】观察分析可得,,,则将此规律用含自然数n(n≥1)的等式表示出来是由分析可知,发现的规律用含自然数n(n≥1)的等式表示出来是故答案为:
-You didn’t wait for Elizabeth last night, did you?
-Yes, but we _________.She didn’t come at all.
[ ]
A.
don’t have to
B.
needn’t have
C.
need to
D.
should have