7. Key Words: vitamin and health
Vitamin D helps ________________________ grow strong and healthy. Low levels of vitamin D can lead to problems such as rickets, a ________________ mainly found in children. But more and more research is suggesting that vitamin D might also help prevent many diseases.
The easiest way to get vitamin D is from sunlight. The suns ultraviolet _____________ react with skin cells to produce vitamin D. But many people worry about _________________________________________ from the sun. As a result they cover their skin or wear sun-block or stay out of the sun.
Also, darker skinned people produce less vitamin D than lighter skinned people. Production also _______________ in older people and those living in northern areas that get less sunlight.
8. Key Words: light pollution
Sunlight bounces off the light-colored surface, so it stays cool on hot days.
areas of cities trap heat. This is known as ________________________________. The Green Alley program also uses _______________ materials. And it uses energy-saving streetlights. These direct light downward to reduce light pollution at night.
Part III Short Conversation
Unit One
1. A) His father. B) His mother.
C) His brother. D) His sister.
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