水准测量中，如果后尺读数大于前尺读数，说明后尺（）
A.高于前尺点
B.低与前尺点
C.低与测站点
参考答案：B
On Sundays there were a lot of children playing in the park, _______ parents were sitting together joking.
A．their
B．whose
C．which
D．that
装配位置关系约束的作用？
