Combine the following sentences using appositive or appositive phrases. use commas as they are needed 1. franklin d. roosevelt was the only child of a wealthy couple. he was elected president four times.

An appositive or appositive phrase are words that are used to rename a noun that is right beside it.  Combining the sentences using an appositive would be:

Franklin D. Roosevelt, the only child of a wealthy couple, was elected president four times.

The appositive phrase is "the only child of a wealthy couple" as it is used to rename Roosevelt. 

Franklin D. Roosevelt, the only child of a wealthy couple, was elected president four times.

Appositive phrases are phrases that rename the noun that comes right before them. So, in this sentence "Franklin D Roosevelt" is the noun. Another way to describe him is "the only child of a wealthy couple". That is the appositive phrase.