v react verbally
v respond to a signal
v give the correct answer or solution to
v understand the meaning of
v give a defence or refutation of (a charge) or in (an argument)
v be liable or accountable
v be sufficient; be adequate, either in quality or quantity
v match or correspond
v be satisfactory for; meet the requirements of or serve the purpose of
v react to a stimulus or command
v. 回答；回复（answer的过去式）