The speaker solves mysteries because

A) he wants to expose the truth.
B) he thinks it is a waste of time.
C) he is bored with watching people.
D) he is very good at choosing sides.

i think you should write from the heart and think what truely makes a hero. i can’t do this for you. even though this is it’s up to you.

we should all just get dogs.

the pronoun reference replaces a noun, but you have to make sure there's no room for confusion.

in the first sentence "her" could be referring to shely or to the sister. the answer there is "shelly called her sister and told her about the new baby."

in the second sentence "it" could be referring to the roof or the floor. the answer there is "since the roof leaks on the family room floor, we need to repair the roof."