—Do you know if we will be free this Saturday?
—I don't know, either. ________ the teacher?
A．Why not to ask B．Why not ask
C．Why do not ask D．Why don't ask
—Do you know if we will be free this Saturday?
—I don't know, either. ________ the teacher?
A．Why not to ask B．Why not ask
C．Why do not ask D．Why don't ask
B
句型 Why not...？＝Why don't you...？用于提出建议，后接动词原形。