设随机变量X～N(1，4)，F(x)为X的分布函数，Φ(x)为标准正态分布函数，则F(3)=()

设随机事件A与B互不相容，且P(A)>0,P(B)>0，则()

Will it be_____ before the professor returns ?

—Would you mind my sitting here ?

— ______ .

Only 5 _____ of the population of America _____ farmers .

I'm sorry I've forgotten to post your letter .

—Never mind . _____ post it myself .

The baby always sleeps with his eyes half_____ .

Generally , the weather in Britain is_____ too cold in winter _____ too hot in summer .

—Why have you changed so much ?

—You don't know I ______ a hard life in the last ten years .

—What's the young man?

—______ .