Ex. 1 pag. 30
I generally associate the adjective "Gothic" with a churc or a cathedral because there are lots of Gothic cathedrals in the most importants Countries, like Canterbury cathedral in England, Notre-Dame cathedral in France, Milan cathedral in Italy.
Ex. 2 pag. 30
1. aisle = navata laterale
2. arch = arco, arcata
3. column = colonna
4. facade = facciata
5. nave = navata centrale
6. pier = pilastro
7. rilief = rilievo 
8. pinnacle = pinnacolo
9. fan vault = volta a ventaglio
10. ribbed vault = volta con nervature
11. spire = guglia
12. steeple = campanile o guglia di torre
Ex. 3 pag. 30
1. A large cathedral-compaign there was in England at the end of the 12th century.
2. A churc was called "cathedral" when it conteined a cathedra or throne for a bishop.
3. The matierials were used to build Gothic cathedrals were timber, stone (the most common was limestone), marble and glass.
Ex. 7 pag. 31
The high towers and pinnacles might symbolise nearness to God, in my opinion. So people built high cathedrals to be more near to God.
Ex. 8 pag. 31
The function of stained glass was instructed illiterate people with drawings. But the ost important function of stained glasses was let God's light into the cathedrals. Because people believed that God was always there with them.