A: clea
B: permissive signal
C: estricting
D: approach
举一反三
- According to the meaning of stop signal, it is divided into absolute signal and permissive signal.
- According to the meaning of stop signal, it is divided into absolute signal and _____.
- 2. Railway signals can be divided into home signal, starting signal, distant signal, repeating signal and shunting signal.
- _____, the train started. A: The signal given B: Giving the signal C: The signal being given D: The signal giving
- ________, the train started. A: The signal given B: After the signal was given C: Given the signal D: A and B
内容
- 0
what is an analog signal? A: Analog signal is a continous values B: Analog signal is a discrete values C: Analog signal is sometimes continous,sometimes discrete
- 1
Normally, the distance between the approach and the main signal is no less than _______ meters.
- 2
Answer the following questions according to the text1、What is a signal?
- 3
Which of the following cell signaling molecules does the neurotransmitter belong to? ( ) A: Chemical signal B: Gas molecules C: Optical signal D: Electric signal
- 4
As an experienced technician， you are responsible for Technical Support. A customer calls to askthe best signal level and noise level for cell phone. How to respond？（） A: -40dBm signal and -90dBm noise B: -50dBm signal and -90dBm noise C: -30dBm signal and -90dBm noise D: -20dBm signal and -90dBm noise