Present perfect or Past Continuous?

Which is correct:

• I’ve worked in the garden all day and now I’m tired. 
• I’ve been working in the garden all day and now I’m tired.

Which is correct:

• What have you done? You’re all wet.
• What have you been doing? You’re all wet.

Which is correct:

• I’ve finished my homework. Now I’m going to watch TV.
• I’ve been finishing my homework. Now I’m going to watch TV.

Which is correct:

• What have you done with my keys? - I haven’t seen your keys.
• What have you been doing with my keys? - I haven’t seen your keys.

Which is correct:

• She’s worked in the garden all morning and she’s still not finished.
• She’s been working in the garden all morning and she’s still not finished.

Which is correct:

• Why are you sweating? - I’ve cut the grass.
• Why are you sweating? - I’ve been cutting the grass.

Which is correct:

• How many biscuits have you eaten?
• How many biscuits have you been eating?

Which is correct:

• How long have you known her?
• How long have you been knowing her?

Which is correct:

• I’ve had piano lessons for over 10 years and I’m still not very good.
• I’ve been having piano lessons for over 10 years and I’m still not very good.

I was sure that I ___________ her before.
 

• had saw
• seen
• had seen