Combine these two sentences using a subordinate conjunction.

charles wanted to buy a new guitar.
charles saved his money for three months.

The correct answer could be: Charles wanted to buy a new guitar after he saved his money for three months.

Subordinate conjunctions are used to connect two sentences or parts of sentences. If you use a subordinate conjunction, then one of the sentences will be subordinate/dependent; if you use coordinate conjunction, then both sentences will be independent.

In the example above, I used the subordinate conjunction AFTER, which means that the clause he saved his money for three months is dependent and cannot stand on its own.

yes its like krisnis like in the air force .

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."