练习：
1. Too much salt raises ones risk for
A high blood pressure.
B heart attacks.
C strokes，
D all of the above.
2. How much salt do most American adults eat per day?
A No more than 1，500 mg
B Closer to 3，500 mg.
C Less than 3，436 mg.
D Closer to 1，500 mg.
3. To improve their blood pressure， people should have a diet
A rich in potassium and sodium.
B rich in potassium and calcium.
C rich in calcium and sodium.
D none of the above.
4. The high-risk groups include those
A who are black.
B who are over the age of 40.
C who are white and young.
D both A and B
5. Packaged， processed and restaurant foods are known to be
A cheap.
B tasty.
C rich in salt.
D healthy.
答案与题解：
1. D 短文的第一段说，吃盐过多会增加罹患高血压，心脏病和中风的危险。
2. B 短文的第二段说，大多数美国成年人的日食盐量接近300 毫克。
3. B 短文的第三段说，采用低钠并富含钾、钙的饮食方式将有利于改善血压。
4. D 短文的第五段说，黑人和年龄超过40 岁的人被视为高危人群。
5. C 短文的倒数第二段说，人们所食用的纳绝大部分来自于包装、加工和饭店食品。