题目内容：

Who hasn't found themselves reaching for the closest food available when they're tired and stressed? More and more research is proving that this isn't all in our mind. Some foods really do lead to a change in our moods (心情)．

Carbohydrate (碳水化合物) for calm

This is how some people medicate(治疗) themselves with food — by reaching for cookies or pasta(意大利面食) whenever they're upset.  Unfortunately, it doesn't always work.  You must eat a meal consisting of 100% carbohydrate, on an empty stomach, to obtain the serotonin (血清素) increase so that you have a good mood.

To get the wished­for effect, you must not eat anything for four hours and then eat at least 30 grams of straight carbohydrate. Dry cereal (谷类食品), a piece of bread with jam, or a potato should do_the_trick.

Protein (蛋白质) for power

Of course, sometimes we don't need to be calm and sleepy.Sometimes we need a great deal of mental concentration, so this is when it's important to mix protein and carbohydrate. The protein will prevent the tryptophan (色氨酸) from flooding your brain，and the rise in serotonin(血清素) won't occur.

Why dessert makes us happy

Fat and sugar cause the brain to let go endorphins (内啡肽), which send pleasure signals throughout the body. This would be fine, except humans are not particularly good at stopping at one cookie or cake.

You can also satisfy your sweet tooth by choosing fruit for dessert.

Timing your meals for energy

Blood sugar drops after four hours of going without food, causing a decrease(减少) in energy. Eating usually fixes this within 20 to 30 minutes, but don't suppose that eating more will cause a faster increase in energy.

When you eat has as much of an effect on your mood as what you eat.  If you regularly go for a long period of time between meals, rethink your schedule and plan ahead.

1.The underlined phrase“ do_the_trick” in the third paragraph means ________.

A．be extremely smart

B．intend to cheat someone

C．bring about the desired result

D．do something to amuse people

2.The function of protein is ________.

A．to help you keep calm and sleepy

B．to make you feel energetic

C．to lead you to slowness

D．to increase serotonin in your brain

3.We can infer from the last two parts that ________.

A．fat and sugar can greatly help people feel happy

B．we humans tend to eat lots of cookies and cakes

C．the more we eat, the faster we will gain energy

D．what we eat is more important than when we eat

4.The main idea of the passage is ________.

A．eating for a better mood

B．eating to make you calm

C．eating for more protein

D．eating to make us strong