The first diagram (1-illustrates) …………………… the process of cement manufacture, and the second diagram (2-shows) …………………… the materials that go into the production of concrete. It is clear that there are five stages in the production of cement, beginning with the input of raw materials and ending with bags of the finished product. To produce concrete, four different materials (3-are mixed) …………………… together. At the first stage in the production of cement, limestone and clay (4-are crushed) …………………… to form a powder. This powder (5-is then mixed) …………………… before it passes into a rotating heater. After heating, the resulting mixture (6-is ground) ……………………, and cement (7-is produced) ……………………. Finally, the cement (8-is packaged) …………………… in large bags. Cement is one of the four raw materials that (9-are used) …………………… in the production of concrete, along with gravel, sand and water. To be exact, concrete (10-consists) …………………… of 50% gravel, 25% sand, 15% cement and 10% water. All four materials are blended together in a rotating machine called a concrete mixer.