I’m hoping that John will let us have the car tonight; __________, I’m afraid we won’t be able to go out.     

A．even if

B．if so

C．what if

D．if not

aVR导联为（）

A．标准肢体导联

B．单极肢体导联

C．加压肢体导联

D．胸导联

E．F导联