He popped his head around the door and said hello.

他从门后探一探头，打了声招呼。

《牛津词典》

They smiled and said hello to each other.

他们微笑着相互打招呼。

youdao

He flew me a kiss when I said hello to him.

我向他打招呼时，他给了我一个飞吻。

youdao

(SINGING) My mama said I didn't knowhow to make a kitty meow (DEEP GROWL) Hello?

VOA: standard.other

you saw an adult, you said hello, you said good morning and you said good afternoon, you know.

每逢遇到一个大人，都会说“你好”，“早上好”，“下午好”，就像这样。

和纽约的留学生 - SpeakingMax英语口语达人

Anyway, if he leaves before I see him, then tell him I said hello.

要是我没来得及见他，他就走了，帮我问候他。

Who 实战 - SpeakingMax英语口语达人

He said hello tersely, then turned his head away from us and continued on.

FORBES: The Body in the Suitcase: How Our Stories Lead Us Astray

Plank spotted Knight on the rainy field before the game and said hello.

FORBES: Under Armour's Kevin Plank Is The Billionaire Underdog

"He just came over and said hello, and I welcomed him, " Chamberlain said.

WSJ: Yankees razz Youkilis for Red Sox remarks