51单片机每一个I/O口引脚都可以独立地做输入口或者输出口使用。
查看答案
51单片机共有4个8位的并行I/O口，其中P2口既可用作地址/数据口，又可用作一般的I/O口。
A. 对
B. 错
Frankly, I'd rather you ______ anything about it for the time being.
A. do
B. don't do
C. didn't do
D. will not do
In Britain, the best time for sighting is ______ spring and early summer.
A. later
B. latter
C. last
D. late
It may be five to ten years ______ we can test this medicine on human patients.
A. since
B. after
C. before
D. when
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