Present perfect or past simple? -What are you doing this weekend? -I dont know....

Question

Present perfect or past simple?

-What are you doing this weekend?
-I dont know. I/not/decide/yet.

-I cant find my adressbook. Have you seen it?
-it/on the table/last night.

-Are you hungry?
-I/just/eat.

-Paula and Sue are here?
-Are they? what time/they/arrive?

Answer 1

- What are you doing this weekend? 
- I don't know. I haven't decided yet.

- I cant find my address book. Have you seen it?
- It was on the table last night.

- Are you hungry?
- I have just eaten.

- Paula and Sue are here.
- Are they? What time did they arrive?