Complete the following sentence by choosing the correct option:
I am tired as _________ since 7 o'clock in the morning.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → I have been working
Present perfect continuous with "since":
- An action that began in the past and is still going on (or has just stopped) takes the present perfect continuous: have/has been + -ing.
- Since gives the point of time when it began (since 7 o'clock). For gives the length of time (for five hours).
- This sentence: the speaker is tired now because the work has gone on from 7 in the morning up to now, so "I have been working since 7 o'clock".
Complete sentence: I am tired as I have been working since 7 o'clock in the morning.
Contrast: have been working runs from a past point up to now. Had been working runs up to another past time.
Why the Other Options are Incorrect?
Option 2: working — Incorrect. "as working since 7 o'clock" has no subject and no helping verb, so the clause is incomplete.
Option 3: I had been working — Incorrect. The past perfect continuous describes an action before another past time. The speaker's tiredness ("I am tired") is in the present.
Option 4: I will be working — Incorrect. The future continuous cannot explain present tiredness and does not go with "since", which looks back to a past point.