题目内容：

    For decades, doctors have warned patients that too much salt can be bad for the heart. Heat attack has long been considered a grown-up problem, but a new research suggests that salt is starting to affect children. Eating too much salty food when you're young can lead to health problems later.

Salt is made up of two elements: sodium and chlorine. Dietary guidelines recommend that adults and kids aged 9 — 13 shouldn't consume more than about a teaspoon of salt daily. The average American eats twice this amount. This worries doctors because too much sodium results in the body producing more blood. To pump the extra blood, the heart has to work harder. This causes a rise in blood pressure a measurement of how stressed the heart is. High blood pressure often leads to heart disease.

A kid with high blood pressure is more likely to become a grown-up with high blood pressure. Reducing salt might also help stop childhood obesity (肥胖). British researchers recently found that kids who eat less salt also drink fewer sugary soft drinks. Drinking fewer fizzy drinks makes kids less likely to gain weight, become obese and develop high blood pressure.

Salt can affect more than just your heart and weight. A recent study found that a growing number of kids in the US are suffering from kidney stones. This painful condition usually affects people aged over 40. Now, kids as young as five are getting it.

Cutting down on salt can be hard, but you can retrain yourself to prefer less salty food. The best way to reduce the amount of sodium you eat is to make changes gradually. Start by adding half as much salt to your dinner as you normally do. Switch to fresh foods instead of canned and bottled versions. And go easy on the condiments (调味品). You might also want to start reading nutrition labels. You may be surprised to learn that there are 1,150 mg of sodium in a double cheeseburger, and over 2 ,000 mg in many frozen meals.

1.What is the author's major concern?

A.Children eat too much salty food. B.Many adults suffer from heart attack.

C.Americans consume too much salt. D.Heart attack is now a youth problem.

2.What does the author refer to as the cause of childhood obesity?

A.Eating more salty food. B.Lack of physical exercise.

C.Drinking many sugary soft drinks. D.Eating the same food as the adults.

3.What is another disease tending to be younger according to Paragraph 4?

A.Obesity. B.Kidney stone.

C.Blood disease. D.Heart attack.

4.What is Paragraph 5 mainly about?

A.The laws of health. B.How to cut down on salt.

C.Healthy diet. D.The amount of salt we need.