always adv. ①总是
eg: He always comes late. 他总是迟到。
②永远
eg: I shall always remember my first day at school.
我将永远记住我上学的第一天。
usually adv 通常，经常
often adv ①多次； 时常
eg: How often do you go there? 你多久去那里一次？
How often you have been abroad? No often, only twice.
你出国几次了？不多，只出去过两次。
②经常；通常
eg: Children often dislike homework.
孩子们通常都不喜欢家庭作业。
He often does this. 它经常干这种事。
sometimes adv 有时，时不时地，间或
eg: I sometimes think that it is a great mistake.
我有时想这是一个大错。
Sometimes I help my mother in the house.
有时候我帮助妈妈做家务。
程度的频繁到不频繁：
always 总是 -- usually 通常 -- often 经常 -- sometimes 有时 - never从不
用法：放在be动词和助动词后面；行为动词前。
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