问题
选择题
--- I phoned you at six yesterday afternoon, but nobody answered.
--- Oh, I __________a walk with my parents near the river.
A．am taking
B．was taking
C．took
D．will take
答案
答案：B
题目分析：句意：-我昨天下午六点给你打电话，但是没人接。-哦，我那时正在和我的父母在河边散步。昨天六点正在做某事，过去某一时刻正在做某事，要用过去进行时态，主语是I，所以系动词用was。故选B.
的小球由静止释放，小球的运动轨迹为一直线，此直线与竖直方向的夹角为θ，则匀强电场E的最小值是
