How long,how much time,how many hours 多长时间,多少时间,几个小时?
How often 是多么经常,多长时间发生一次.
help 动词原形,
helpful形容词,有助的,
helped 过去时,过去分词.He helped me before.He has just helped his mother cook dinner.
helps 一般现在时,第三人称,动词原形后面加 s.He helps his mother cook dinner everyday.