tongxun

1.st不等于0，s-1/s<1/t-t,s-t>0? 1) s>1 2) t>0 ----------------- condition 1) (1-t^2)/t >0 => -1 2s^2 -3s -2<0 =>(2s+1)(s-2)<0 => s<-1/2 or s>2 so this condition alone is not sufficient. The answer should be A