PWM脉宽调制
参考答案:
是靠改变脉冲宽度来控制输出电压,通过改变周期来控制其输出频率。
Writer Guo Jingming's latest book Tiny Times 3.0 has sold 1.4 million copies in _____ three months
since its release last December. It is______ new height in ______ writer's career. [ ]
A. /;a;a
B. the; a; the
C. a; the; /
D./; the; the
《本草纲目》为后人留下了较完备的医药知识,人们在秉承这些医药知识的同时,其作者在行医时常为病人送药、煎药、喂药的高尚医德更为后人所称道,此人为()
A.孙思邈
B.张仲景
C.李时珍
D.龚延贤
E.喻昌