超声检测羊水过少，下列哪项可能性最小()
A．无脑儿
B．过期妊娠
C．肾发育不全
D．羊膜早破
E．胎儿水肿
参考答案：A
They went to the Great Wall ______ vacation last year.[ ]
A. at
B. on
C. to
D. in
