Winter is the best season. I have a ________ holiday at that time ________ I have a lot of fun. I love ________ days because everything ________ white. It is exciting ________ snowmen and spend time ________ in the snow with my friends.

I like to ________ my relatives during the Spring Festival in January or February. We always have dinner ________. Sometimes I go on a trip with my parents ________ the winter holidays. We always have a ________ time.

Do you find it difficult to refuse a piece of cake after dinner, or to read books instead of surfing the Internet? You know something’s bad for you, but you just can’t stop it. Why? Well, researchers have found a reason why bad habits are so hard to break — they get hard-wired(本能的) into our brains.

Scientists from Duke University in the US have studied what happens in our brains as habits form. According to their research, our bad habits leave a _______ that stays in an area of the brain that controls compulsive(无法控制的) behavior and addiction(瘾). It then pushes us to give in to our wants without us even knowing it.

In order to prove this point, the Duke scientists did an experiment with mice. First, they trained a group of mice to press a small lever(杠杆)to get a sugary treat. When the sweets were taken away, these sugar-addicted mice continued pressing the lever, _______ there was no sugar.

Why did this happen? According to scientists, in an area in our brain known as the basal ganglia (基底核), there are two pathways. They give two messages: one pathway is “go”, the other is “stop”. In the brains of sugar-loving mice, researchers found that both the “go” and “stop” signals (信号) were more _______ than those of other mice. Moreover, the “go” pathway lit up before “stop” for the mice that had formed the habit.

The head start of the “go” pathway could explain why we can’t _______ from that delicious cake. But you may ask why good habits, like exercising every day, can’t occupy(占领) the “go” pathway. Why is it hard to fall into good habits through doing something good again and again?

According to Russell Poldrack, a neurobiologist (神经生物学家) at the University of Texas at Austin, US, all the habits _______ the same types of brain actions, but habits that give you pleasure can make your brain release dopamine(多巴胺). It makes you want the pleasure again and again.

It seems that parts of our brains make it difficult for us when we try to overcome bad habits. But good news is that we are not _______ of habit. We can always make the right choice using many other parts of our brains.

Perhaps you ride a bicycle to school. Riding a bicycle can be great fun. Do you know how to ride a bicycle ______ ?

Careful boys and girls learn to ride their bicycles well ______ they go out on the road. How can you tell ______ you are a good rider? If you can ride a bicycle in a straight line, you can ride well. If you can’t, you should practice riding ______ safe place. To be safe on a bicycle, you ______ use both hands and both feet. ______ your feet on the pedals and your hands on the handle bars at all times. Do you have a ______ on your bicycle? If so, put your books and packages in it. You know that most bicycles are built for ______ person. It is not safe to carry anyone ______ you.

Keep ______ safe by following safety rules when you ride a bicycle. Watch where you are going at all times.