Fill in the blank using present perfect: I (not / work) __________ today.
I (not / work) have not worked today.
Fill in the blank using present perfect: We (buy) __________ a new lamp.
We (buy) have bought a new lamp.
Fill in the blank using present perfect: We (not / plan) __________ our holiday yet.
We (not / plan) have not planed our holiday yet.