1. [单选题]Every valid character in a computer that uses even ______ must always have an even number of 1 bits.
A. parity
B. check
C. test
D. compare
2. [单选题]计算机软件两大类可分为______
A. 操作系统和数据库
B. 数据库和应用程序(application)
C. 操作系统和语言处理程序
D. 系统软件和应用软件
