Please provide answers to the following three exercises/questions

Please provide answers to the following three exercises/questions.

 

1. Please provide a natural deduction proof for the following valid, deductive argument:

Premise 1:  ~ ( F & A )

Premise 2:  ~ ( L v ~ A )

Premise 3:  D > ( F v L )              / ~ D

 

2. Answer the following question:  can one invalidity with the natural deduction proof method?  Why or why not?

3. Answer the following the question:  can one construct a natural deduction proof for an invalid argument in SL?  Why or why not?