Not "I have anything to tell you." — say "I have something to tell you.". 普通肯定句用 some- 系列的词，不用 any- 系列的词。
试一试: There is ___ at the door. I can hear them. (somebody / anybody / nobody) 答案: somebody — 这是一句普通的肯定句（真的有一个人在），所以用 somebody。"Anybody" 用于否定句和疑问句，"nobody" 会表示那里没有人。
Not "I don't have something to say." — say "I don't have anything to say.". "Don't have" 让这句话变成了否定句，所以 something 变成了 anything。
试一试: Did you see ___ at the station? (anyone / someone / no one) 答案: anyone — 这是一个疑问句，所以用 anyone：Did you see anyone? "Someone" 用于普通肯定句，"no one" 已经表示你没看到任何人了。
nothing, nobody, nowhere
no- 系列的词本身就已经表示否定了：nothing, nobody / no one, nowhere。所以后面的动词要用肯定形式，不要再加一个 not。
Nobody came to the meeting.
Nothing happened.
There is nowhere to sit.
Not "I don't have nothing." — say "I have nothing. / I don't have anything.". nothing 已经表示否定了，所以不要再说 don't，只能选一个。
试一试: The fridge is empty. There is ___ to eat. (nothing / anything / something) 答案: nothing — 动词 "is" 是肯定形式，而你想说的是什么都没有，所以用 nothing：There is nothing to eat。"Anything" 前面需要先有一个否定词（isn't anything），"something" 则表示有食物。
试一试: Which one is right? (We saw nobody. / We didn't see nobody. / We don't saw nobody.) 答案: We saw nobody. — Nobody 本身已经表示一个人都没有，所以动词要用肯定形式：We saw nobody。"Didn't see nobody" 相当于用了两次否定。（你也可以说 "We didn't see anybody."）
everything, everybody, everywhere
every- 系列的词表示全部：everything = 所有东西，everybody / everyone = 所有人，everywhere = 所有地方 / 每个地方。虽然它们说的是很多，动词却保持单数（比如 is / was / has）。
Everybody is here now.
She told me everything.
I looked everywhere for my keys.
Not "Everybody are happy." — say "Everybody is happy.". Everybody 指的是所有人，但动词要用单数：用 is，不用 are。
试一试: The party was great. ___ had a good time. (Everybody / Anybody / Nobody) 答案: Everybody — 你想说的是所有人都玩得开心，所以用 Everybody。"Anybody" 用于否定句和疑问句，而 "nobody" 会变成没有人玩得开心。
试一试: I looked everywhere, but I couldn't find ___, so in the end I bought ___ new. (anything … something / something … anything / nothing … anything) 答案: anything … something — "Couldn't find" 是否定句 → anything。"I bought" 是普通肯定句 → something。否定句用 any-，肯定句用 some-。