— Must I clean my bedroom this afternoon,Mom?
— No,you ______. You can do it tomorrow,dear.
need't
mustn't
can't
won't
情态动词。
用must提问的句子，否定回答用needn't 或 you don't have to，表示不必。
— ________ do you eat out,Molly?
— Once a month.
How often
How far
How long
词义辨析。
How often意为“多久一次”； How far意为“多远”； How long意为“多长时间”。