Vitamins are essential to the body. Vitamin A helps keep the skin smooth and son. When it is absent, the skin becomes thick and rough. Another important vitamin is thiamine or Vitamin B1. Many people who complain of being tired and irritable are actually suffering from lack of thiamine. 12. What is the main idea of the paragraph? A. Sources of Vitamin A and Vitamin B1 B. Why vitamins are essential to the body C. How to keep the skin smooth and soft D. Thiamine or Vitamin B1 13. What is the purpose of the author in writing the paragraph? A. To describe B. To classify C. To explain D. To compare and contrast 14. I could hear the distant sound of pots clattering in the kitchen as Grandma fred me up a hom cooked meal, and Laney, their cow, faintly mooed in the distance. A. Cause & Effect B. Comparison & Contrast C. Problem & Solution D. Description 15. In northern areas, the weather is too cold to grow crops all year long. But some farmers have found a way to grow food all year. A greenhouse is a special building that stays warm in the winter. Crops like lettuce and basil can grow well in the greenhouse, even when the weather is cold. A. Cause & Effect B. Comparison & Contrast C. Problem & Solution D. Sequence 16. In several ways, noise can be harmful. Loud noises may damage a person's hearings. Noise ha also caused people to become tired and nervous. It makes work unpleasant and burdensome. Today, concerned people are doing something about noise polition​