题目

The young man ________ the beautiful girl when he saw her for the first time.A．felt in love withB．fell in love toC．fell in love withD．felt in love to 答案：C解析:略化简cos(α+β)cosα+sin(α+β)sinα得(    )A.cosα              B.cosβ               C.cos(2α+β)            D.sin(2α+β)