使用顶焦度计测量前必须调整物镜视度，使其适应测量人员眼睛的屈光状态。
参考答案：错
若| a﹣b+3| +| 2a+b|=0 ，先化简再求值：2a3b(2ab+1) ﹣a2( ﹣2ab)2．
Frank _____ to see his grandma if he _____ free tomorrow.
A．will come ; will be
B．comes ; is
C．will come ; is
D．is; come
