单选题 Vitamin D is necessary for health and growth. It is used by the body to form strong bones and teeth. That is why growing children need it.
Vitamin D is also called the sunshine vitamin. It forms when the skin is exposed to the sun. In the past people Blew what vitamin D was they learned that sunshine was important. Poor children lived in crowded slums (贫民窟). And they were often ill with tickets (软骨病). In England a tax was once placed on windows. Builders put few windows in houses. Rickets became so common that it was called the English disease.

单选题 One good way to get vitamin D is to ______.

A、 sleep with your windows open
B、 play in the sunshine
C、 eat plenty of fresh vegetables
D、 take some medicine

【正确答案】 B

【答案解析】[解析] 从文章第二段第二句：It forms when the skin is exposed to the sun. 得知。故本题答案为B。

单选题 Because adults have reached full growth, they probably ______.

A、 need as much vitamin D as children
B、 need less vitamin D than children
C、 need more vitamin D than children
D、 need no vitamin

单选题 The increase of rickets in England was caused by ______.

【正确答案】 B

【答案解析】[解析] 从文章第二段第四、五、六句得知。故本题答案为B。