Pizza is certainly one of the world’s favourite     1     (food). But where does pizza come from? And who made it the first time?

In fact, people have been making pizza for a very long time. People     2    lived in the Stone Age cooked grains on hot rocks to make dough(生面团)—the basic ingredient of pizza. Over time, people used the dough as a plate,    3    (cover) it with various other foods. They had developed the world’s first pizza. In    4    early 16th century, European explorers had tomatoes     5    (bring) back from the Americas. Tomatoes are a standard ingredient in pizza today. At first, however, most Europeans thought they were     6    (poison).    7     (actual), only the leaves and roots are. For about 200 years, few people ate them. Slowly, people learned that tomatoes were safe    8    (eat), as well as tasty. In the early 19th century, cooks in Naples, Italy, started the tradition of putting tomatoes on baking dough. The flat bread soon became popular with poor people all over Naples. In 1830, cooks in Naples took another big step    9    pizza history—they opened the world’s first pizza restaurant. Today, up to five billion pizzas    10    (serve) every year around the world.