多电源或双侧电源系统中电流保护动作定值或动作时间不能保证选择性时,需要利用保护动作的的方向性保证选择性。( )
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[音频]
A. Long-time exposure to ear pressure.
B. Long-time exposure to loud sounds.
C. Listening to music without wearing fashionable earphones.
D. Listening to music without wearing specially-made earplugs.
[音频]
A. Wear your earphones wherever you go.
B. Follow the fashion of wearing earplugs.
C. Wear earplugs in case of high-volume sounds.
D. Buy expensive earplugs to protect your hearing.
When the serial port of AT89S51 extends the parallel I / O port, the working mode of the serial interface is selected.
A. Mode 0
B. Mode 1
C. Mode 2
D. Mode 3
The register that controls the working mode of the serial port is.
A. TCON
B. PCON
C. TMOD
D. SCON
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