题目

The teacher is ____ with what we did.A．pleasedB．pleaseC．pleasureD．pleasant 答案：A解析:略在△ABC中，lgsinA，lgsinB，lgsinC成等差数列，是三边a，b，c成等比数列的（ ）A．充分非必要条件B．必要非充分条件C．充要条件D．既不充分又不必要条件