18. how long/how often
how long意为“多久”、“多长”,用于提问时间或距离的长短。如:
How long were you away last year? 去年你缺席多长时间?
How long is the Great Wall? 长城有多长?
how often意为“每隔多久,每隔多长时间”。回答表示程度的频度副词有sometimes, always, usually,
never等或once
a week, three times a month等。如:
How often do you go to see your mother? 你每隔多长时间去看你的母亲?
此外,how
far意为“多远”(对距离提问);
how old“多大”(对年龄提问);
how many“多少”(对不可数名词数量提问)。