【单选题】--Do you know him well? --Sure. We friends since ten years ago.
【单选题】— How do you like your Englsh teacher? — He is great. We friends since three years ago.
【单选题】考生的成绩近似服从正态分布,平均成绩为μ=73,标准差为σ=10,求考生的成绩低于86分,即P(x≤86) ?( )
【单选题】—Do you know him well? —Sure. We friends since ten years ago.