"By no means" in line 4 means ______.

A．since speakers will inevitably be affected by the recording one should not study such effects
B．since speakers will inevitably be affected by the recording one should deliberately study such effects
C．since speakers will not be affacted by the recording one should not study such effects
D．since speakers will not be affected by the recording one should deloberately study such effects

A．place where the police hide in order to trap motorists
B．parts of the road which are deceptive to the driver's eyes
C．danger spots such as sharp corners and cross-roads
D．places where there are too many road-signs