题目

已知为锐角，且2tan(π－)－3cos(＋β)＋5＝0，tan(π＋)＋6sin(π＋β)＝1，则sin的值是( ) A.     B.     C.      D. 答案：C Although the lecture had already been on for five minutes, I still was not able to find a chair ________． [　　] A． to sit B． for to sit on C． to sit on D． for sitting