B, if you only study for a few minutes in each subject each night you have the chance to review what you studied the night before
The correct answer is Sentence 9.
The sentence should be written: Sadly, even after that water is found, only some of it's clean and safe enough to drink.
We know an apostrophe should be placed here because we could also say: Sadly, even after that water is found, only some of it is clean and safe enough to drink.
