题目

— Will your brother stay home tonight? — I’m not quite sure. He _____ to the cinema tonight.  A. must go       B. can go       C. may go      D. may be going 答案：C 解析: 表示推测时，must比may语气肯定。6．已知在△ABC中，a、b、c是∠A、∠B、∠C所对的三边，G为△ABC的重心，且满足4a•$\overrightarrow{GA}$+2b•$\overrightarrow{GB}$+3c•$\overrightarrow{GC}$=$\overrightarrow{0}$．（1）求cosB的值；（2）如果△ABC的周长为13，△ABC的内切圆的半径为$\sqrt{35}$，求△ABC的面积．