【单选题】We began to open to the outside world in the late 1970s. ,there have been great changes in the country.
【简答题】二进制数11011.1转化为十进制数是( )
【单选题】Great changes in the past 20 years.
【简答题】设A,B是两个事件,已知P(A)=0.5,P(B)=0.7,P(A∪B)= 0.8,试求: ( 1)P(AB);(2)P(A-B);(3)P(B-A).