【正确答案】 A

【答案解析】[听力原文] 17-20
Many foods contain substances that protect against tissue damage. One of these is tomatoes. When tomatoes are cooked, [17] a certain substance that helps reduce the risk of developing cancer in the digestive system is released.
The dark green vegetable spinach can prevent problems in developing embryos. It also lowers blood levels of homocysteine. [18] High homocysteine levels have been linked to heart attacks and strokes, Another vegetable, broccoli, can help protect against cancers of the breast, colon and stomach.
Oats help lower blood pressure and protect against heart disease. [19] They also may improve the levels of sugar in the blood. This reduces the chance of developing the disease diabetes.
Fish that contain omega 3 fatty acids help prevent blockages in the arteries. Omega 3also lowers bad cholesterol and may protect brain cells from diseases that prevent the brain from functioning normally. Fish that provide a lot of omega 3 acids are salmon and herring.
[20] Garlic may help protect the heart by reducing cholesterol and making the bloodless sticky; Health experts also suggest cooking with olive oil because it also has been shown to help prevent cancer and heart disease.
[考点] 本题出题点在细节处。
[精析] 短文提到，番茄烹饪后，会释放出一种可以降低消化系统发生癌变的几率的特殊物质，故选A。