I was graduated from senior high school is the old fashioned way to say it, but because more and more people just use "I graduated....", so it became the more commonly used one. According to The American Heritage Dictionary Traditionally, the verb graduate denotes the action of conferring an academic degree or diploma, and this sense has often been conveyed in the "PASSIVE VOICE", as in They were graduated from Yale in 2010. This usage still exists, though it is somewhat old-fashioned and may be slipping away. In our 1988 survey, 78 percent of the Usage Panel accepted this sentence, but almost half the Panel FOUND IT UNACCEPTABLE IN OUR 2006 SURVEY. For your information: https://ahdictionary.com/word/search.html?q=graduate&submit.x=0&submit.y=0

哇!!你人好好!!!真的很謝謝你耶!!!!我明白了~!! <3

我又查了一下，i was graduated 用法有些过时了，现在大多数人都用 i graduated from. 来源于The American Heritage Dictionary, 你可以自己再查一下。

Hurry Swift got it! thank you very much :")

“I graduated from senior high school three days ago.” is even much better. Because in English speaking countries, we do not usually use the present continuous tense to express something like that.