The intracellular small molecules which can transmit extracellular signal is called ( ) A: first messenger B: carrier C: second messenger D: transmitter E: third messenger

Small molecules which are responsible for intracellular signal<br/>transduction are called( ) A: receptor B: vetor C: transmitter D: first messenger E: second<br/>messenger

_____, the train started. A: The signal given B: Giving the signal C: The signal being given D: The signal giving

2. Railway signals can be divided into home signal, starting signal, distant signal, repeating signal and shunting signal.

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

________, the train started. A: The signal given B: After the signal was given C: Given the signal D: A and B

According to the meaning of stop signal, it is divided into absolute signal and _____.

According to the meaning of stop signal, it is divided into absolute signal and （ ）. A: clea B: permissive signal C: estricting D: approach

According to the meaning of stop signal, it is divided into absolute signal and permissive signal.

In<br/>the hybrid equivalent model, hfe<br/>is the expression for __()()____. A: input impedance B: voltage feedback ratio C: small-signal current gain D: output admittance