Do we need subjects to fully and correctly make sentences?
 

I am wondering if we can have Japanese sentences that not having any subject. Like ”にほんごをばんきょします。” Is it correct and proper to say so, or should it be "私を日本語のばんきょします”

BTW, correct the sentences if there are mistakes. I am just a beginner. ^^

It is very common to have sentences without subjects. Usually "I" or "you" is dropped, and often the subject is dropped when it is clear what is being discussed.

にほんごをばんきょします。

にほんごをべんきょうします。

私を日本語のばんきょします

私が日本語のべんきょうします。

I see. Thank you MMM

BTW, why in the second sentence, it should be が instead of を　？

It's because Japanese is one of the fewest topic-prominent languages in the world. It's not 100% subject-oriented like English.

が comes after the doer of a verb.

を indicates "object" and is what the verb is done to.

私がりんごを食べます。 I eat an apple.

I got it. Thanks. You are really helpful. I am happy that I found this forum.