根据单项式的定义可知，在这一组数中0，-3a，x3，16，4mn，x2y是单项式．
---I think maths is playing a more important part in the new test system. What about you? --- ______. We should be more devoted to it.
A．No pains, no gains.
B．Fact speaks louder than words.
C．Great minds think alike.
D．Don’t claim to know what you don’t know.
20世纪60年代，由于软件生产的复杂性和高成本，使大型软件生产出现很大困难，人们称之为 ______ 。
