Confusing Words

The _____________ of thoroughly studying was passing the test.
effect
affect

This music positively _________________ my mood.
affects
effects

The list of side ____________ for that drug took the whole commercial break.
effects
affects

That documentary deeply _______________ me.
affected
effected

____________ I have a snack?
May
Can

I _______________ do a back flip.
can
may

I ____________ see the mall from here.
can
may

I _____________ decide to join you.
may
can