"take it serious"
"take it seriously"
"take it seriously"が正しい
the correct form is seriously because "take" needs an adverb, not an adjective
どこかで"take it serious"と聞いたことがあるからまったく違和感を感じてこなかったけど、文法的に説明されると確かにseriouslyの一択だ。
In some dialects, especially US ones, people use adjectives instead of adverbs like this, so it's heard quite often in informal speech. In writing, however, it's wrong.
"take it seriously"が正しく"take it serious"は口語的でフォーマルでは避けたほうが良いようだ。
Both, but most purists would advise to use the adverb seriously to modify the action verb take.
A more sophisticated writer/speaker might us the adjective serious with the elliptical or implicit “as”: I can’t take it (as) serious.
Use the adverb seriously if you want to be taken seriously by those not aware of this less familiar but correct construction.
take it as seriousのasが省略されているとする説。
とはいえ"take it seriously"が多数派だったので、これからは"take it seriously"のみを使っていこうと思う。
ところでtake it easyはどうなのか？
take it easilyとは聞いたことがない！
通例口語体の慣用的表現に用い，他は easily を用いる》.
So, this is bad English?
Take it easy
Take it easy
Don't let the sound of your own wheels
Drive you crazy
If "Take it easy" isn't bad, "Take it serious" should be OK too, should it not?
Although it is a very common phrase, "Take it easy" is technically wrong, because it uses an adjective as an adverb. It is idiomatic and its almost universal usage puts it beyond correction, but that doesn't make it a model for using other adjectives as adverbs.