Children need a healthy,     1    (balance) diet that gives them enough energy to grow and develop. This means that it's necessary for them    2    (take) in more energy than they use and this extra energy forms new tissues as they grow. However, if children regularly take in too much energy, this is stored as fat and they will put    3    weight.

Childhood obesity is one of the most serious public health    4    (challenge) of the 21st century. The problem is global and is    5    (steady) affecting many low-income and middle-income countries, particularly in urban settings. The trend has increased at an    6    (alarm) rate. Globally, the number of overweight children under the age of five    7    (be)estimated to be over 42 million. Close to 35 million of these are living in developing countries.

The causes of obesity are complex and include genetic, biological, behavioral and cultural factors. Obesity occurs when a person eats    8    (many) calories than the body burns up. If one parent is obese, there is a 50 percent chance    9     　their children will also be obese. However, when both parents are obese, their children have    10    80 percent chance of being obese. Less than 1 percent of all obesity is caused by physical problems.

3 . Happiness means different things to different people. For Mary, who has     1     severe sleeping problem, happiness is as simple as having a good night’s sleep.

Bed was once a place     2     Mary went to rest after a long hard day.     3    , she has not had a full night’s sleep in almost six months. Her doctor said that     4     (count) sheep might help her fall asleep. She tried this, but soon got tired of it after it failed to work. She finds the nights without sleep almost     5     (bear) . She is always sleepy and lacks energy during the day.

Mary is not alone. Studies show that more than one in three people worldwide struggle with getting enough sleep. It often takes on different     6     (form): some people can get to sleep, but wake up much too early; some get a full night’s sleep, but are     7     (disappoint) to find that they still feel tired when they wake up; others, like Mary, find     8     difficult to fall asleep in the first place.

Specialists say that people should not worry too much about this problem. In most cases, a lack of sleep     9     (cause) by anxiety and pressure. It is important to keep yourself     10     good spirits and to be positive.