In the following questions, choose the answer that completes the corresponding space in the paragraph below.

In the 15^th century, a man called Lorenzo Ghiberti spent 50 years of his life making four doors for a religious building in Florence, Italy. The doors (which still serve as entrances to the __1__ [building,)/building),] instead of being made of wood, are made of bronze. (This is one reason Ghiberti took so long to finish __2__ [them)./them.)] Each of the first two doors has 28 different panels, each depicting a different religious theme. After working on these doors for 21 years, Ghiberti began a second set of doors (often called the Gates of __3__ [Paradise.)/Paradise).]