题目

下列函数中，既是偶函数又存在零点的是( ) A．y＝cos x                     B．y＝sin x C．y＝ln x                      D．y＝x2＋1 答案：A--I can’t find John .Where did you meet him this morning? -- It was in the hotel _____ he stayed. A．whyB．whereC．whichD．What