A．effectB．voiceC．efficiencyD．sound

This medicine is （).A. efficientB. effectiveC. efficiencyD. effect

【C17】A．actB．voiceC．behaveD．do

【C18】A．effectB．operationC．useD．power

【C14】A．effectB．phenomenonC．crisisD．problem

He speaks German, but his native（)is French.A. tongueB. voiceC. accent

A．effectB．inferC．signifyD．cause