Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 34 to 40.

Real, or original, pizza is an art: the pizzaiolo - the specialist pizza chef - is baker, fire stoker and cook. A wood-burning oven is an essential part of the proceedings. However, before the pizzas get to the fire, they have to be properly shaped and it was this procedure that was causing me all the grief.

Francesco Sarritzu, the pizzaiolo at The Park restaurant in Queen's Park, London, where I went to be trainee for the evening, made it look easy. He showed me what to do and I tried to take it in. The chilled dough balls, pre-weighed at 170 g , were all ready in a special fridge below the work counter. The dough was sticky and Francesco worked fast. First, it was dropped into a large pile of flour and then it was mixed with a small handful of polenta.

From here it was all hands. He pressed out the dough with his fingers, all the time working in flour and pressing the edges out until a small round circle had emerged. He then threw it into his hands, twirling it to shake off the excess flour. He did not toss it in the air. "Tossing is for show,' he said disdainfully. "It is not necessary.' Once the flour was shaken off, he put the dough onto the steel work surface with one half of it hanging over the edge. One hand pressed and stretched and the other pulled in the opposite direction. Before you could say 'pizza Margherita', there was a perfect circle ready to be topped.

I moved nervously into position to have a go at achieving the same result myself. I scooped up a piece of dough from its snug tray. It immediately stuck to my fingers and when I threw it at the flour, it just remained stuck. I had to pull it off. The first bit is easy, or so it seems, but unless you follow the right procedure you sow the seeds of later failure.

The object is to press out the edges, not the centre, using the flour to dry out the stickiness. However, the temptation to press everything in sight to make it stretch into a circular shape is too strong; before I knew it, I had thick edges anda thin centre. Then, a hole appeared in the centre. I was defeated. My second pizza went where the first one had gone: on the fire. We all watched it go up in flames.

Later Francesco showed me that there was a point in the deep oven away from the fire, where the pizzas go when they are first put into the oven. That is putting the long handle deep into the oven, feeling the heat on the arms, and bringing it back sharply.

Some waste materials _______ methane pollute the environment. A. release B. released C. releasing D. to release