课时作业(十二) [必修3 Unit 2 Healthy eating]
(限时：45分钟)
Ⅰ.语法填空
Vitamins are complex chemical substances 1.________ (find) in many foods. The human body needs them for health and 2.________ (grow). The body makes some vitamins, 3.________ usually in amounts too small to meet its needs. 4.________ vitamins are not made in the body. These must be supplied. No one knows exactly 5.________ all vitamins work. Doctors 6.________ know that vitamins have very special uses. One vitamin 7.________ cannot take the place of another. The steady absence of one vitamin in 8.________ otherwise complete diet causes a deficiency disease. Rickets, scurvy, and pellagra are examples of deficiency diseases.
It is best to obtain vitamins 9.________ eating the foods in which they occur. There are also pills that contain a single vitamin or a combination of vitamins. People should consult 10.________ doctors before they take any vitamin pills.
Ⅱ.阅读理解
