YOU SAID:
I am really tired because I studied french last night
INTO JAPANESE
昨夜フランス語を勉強したので本当に疲れました
BACK INTO ENGLISH
I was really tired because I studied French last night
INTO JAPANESE
昨夜フランス語を勉強したので本当に疲れました
BACK INTO ENGLISH
I was really tired because I studied French last night
That didn't even make that much sense in English.