构造一个40键的矩阵键盘,最少需要()条I/O线。
A.12
B.14
C.20
D.40
参考答案:B
编写一个用户自定义函数SGN(),当自变量为正数时,返回1;当自变量为负数时,返回 -1;当自变量为零时,返回0。
I want to buy a car for my father, but haven’t found he likes yet.
A.it
B.that
C.one
D.this