题目

若实数a,b满足0＜a＜b且a+b=1,则下列四个数中最大的是（    ）A.          B.a2+b2              C.2ab          D.a 答案：思路解析:∵a+b=1,a+b＞,∴2ab＜.由a2+b2＞2()2=2×=,又0＜a＜b且a+b=1,∴a＜,∴a2+b2最大.答案:B—Is it serious, doctor?—Don’t worry. ________ serious.A. Nothing B. Something C. Everything D. Anything