题目

Jack _______ yet last night, otherwise he _______ me. A. mustn’t have arrived; must have phoned B. can’t have arrived; would have phoned 答案：B 解析: 否定推测要用can’t/couldn’t+…;与过去事实相反的虚拟语气,条件句用过去完成时态,主句用过去将来完成时态,即would/should/could/might+have+p.p.。设方程x2-mx+1=0两根为α，β，且0＜α＜1，1＜β＜2，则实数m的取值范围是    ．