题目

点M(2，-3，5)到Ox轴的距离d等于( ) A.          B.          C.          D. 答案：B 解析:点M(2，-3，5)到Ox轴的距离为.The old couple have been married for 50 years and never      with each otherA．they had quarreledB．they have quarreledC．have they quarreled D．had they quarreled