― Is he a ?
― Yes, he is.
A:pilot
B:student
C:farmer
I didn't hear your call because I ______ to music at that time.
将一枚骰子先后抛掷两次,若第一次朝上一面的点数为a,第二次朝上一面的点数为b,则函数y=ax2-2bx+1在(-∞,12上为减函数的概率是 ( )