"I have become sleepy, because I did not sleep much last night"
What in the textbook:
What I think is right:
This question is fantastic for studying tense. I'll start with the English, then go to the Japanese.
I have become sleepy, because I did not sleep much last night.
I think that we can agree that the second part (
because I did not sleep much last night.) is past tense, but what about the tense of the first four words?
If you're like me, saying that it is present perfect tense seems to imply present tense (it is technically), but there is also an element from the past involved. From this source:
Present perfect tense combines the present tense and the perfect aspect used to express an event that happened in the past that has present consequences. This tense is used to show a link between the present and past and is commonly used in everyday conversations, in the news, on the radio, and when writing letters.
Japanese present perfect tense is less obvious to the untrained eye than it is in English. This website might come in handy, but there is one particular part from the the discussion on that page that I'd like to highlight:
Past tense indicates that actions were completed in the past, e.g. I studied Japanese. Present perfect tense has a number of different functions, e.g. to express completion: “I have just done my homework,” and experience: “I have studied Japanese before.” In English, you distinguish the two tenses by using “have.” However, in Japanese, we express the two tenses by using the same form. (emphasis added)
In other words, to express the present perfect
have become in Japanese, you would use
I must applaud your attention to detail, as this is something I have never studied or noticed about present perfect tense in Japanese. It appears, however, that your textbook was correct with its verb conjugation.