the children stood in a circle

答案为 A.

A:in a circle 意思为 成圆圈,联系上文表示站成一个圆圈,实际的圆圈

B:a用于辅音前;an用于元音前.因此B错误

C:in the circle 意思为按照圆圈,虚拟存在的圆圈.例句Each child

in a circle repeats a message to the next child

in the circle in a

whisper.

D:Instead they

move in circle

around the earth.取而代之的是他们反而绕着地球运转.