The human body is a living machine ,and, like all machines, it needs fuel to supply it with energy. This is provided by the food we eat. But how much do we need to stay healthy?

The energy value of food is usually measured in calories. A calorie is the amount of heat required to raise the temperature of 1 kg of water by 1℃.The number of calories people need per day is different, as the chart below shows. Also, the number of calories you use at any moment normally depends on the activity you are in. For example, you need more calories for standing than for sitting, more for running than for walking, and so on.

The energy in food is mainly in the form of three kinds of chemical materials—carbohydrate（糖类）,protein and fat. Carbohydrate provides 3.8 Cal/gm（calories per gram） of energy, protein 4.0 Cal/gm and fat 8.8 Cal/gm. Each food contains different amounts of these materials, as the second chart shows.

Chart Ⅰ

Chart Ⅱ

1.____ calories are required to raise the temperature of 5 kg of water from 35 ℃ to 90 ℃?

A.55　　　　　　　　 B.175　　　　　　 C.325　　　　　　 D.275

2.If you lack for calories to support your running activities you’d better take more ____.

A. milk　　　　　　 B. peanuts C. rice　　　　　　 D. milk and rice

3.We may learn from the charts that ____.

A. a child aged eight requires more than 3 times the amount of calories that a baby does

B. a boy aged sixteen requires nearly twice the amount of calories that a boy aged eight does

C. a mother with a baby to feed uses up more calories than a hard-working farmer each day

D. an old man needs less calories than an 8-year-old boy on account of his less movement

4.Which of the following statements agrees with the passage and the charts above?

A. You need more calories for swimming that for mountain climbing.

B. If you take an equal amount of Vitamin containing the calories you need, you don’t need to eat any food at all.

C. Different people need different amounts of energy depending on their age, sex and the activities they are in.

D.3 grams of milk provides 16.6 calories because carbohydrate provides 3.8 Cal/gm, protein 4.0 Cal/gm, and fat 8.8 Cal/gm.

The human body has hundreds of muscles. The three types are skeletal(骨骼的) muscles, smooth muscles and cardiac, or heart muscles. Each kind of muscle has a special job to do. 
The skeletal muscles are attached to the bones; they actually hold the skeleton together. Strong cords, called tendons(肌腱), help connect these muscles to the bones. Skeletal muscles give us strength and allow us to move in many ways. If you look at skeletal muscles through a microscope, you will see that it has bands of fibers that look like stripes(条纹). These stripes are called striations. Skeletal muscles usually move because the brain has sent a conscious message to them telling them what to do. This is called voluntary movement.
Another type of muscle is smooth muscle. Unlike skeletal muscle, smooth muscle does not have striations. This is found in organs such as the stomach, the bladder(膀胱), the lungs and the eyes. Smooth muscles are smaller than the skeletal muscles and they move involuntarily. The brain tells these muscles what to do, but we aren’t even aware of it. For example, we don’t have to think about breathing or digesting food. The smooth muscles just do their jobs automatically. For this reason smooth muscles are sometimes called involuntary muscles.
Like smooth muscle, cardiac muscle also works involuntarily. It is a very thick muscle that is found only in the walls of the heart. Its job is to pump blood out of the heart and into blood vessels called arteries(动脉). The arteries help carry the blood to all parts of the body. When the cardiac muscles relax, they let blood back into the heart. Cardiac muscles have striations, just like skeletal muscles do.
【小题1】When we _______, the job is done by smooth muscles.

The human body consists of organs, each ____a definite job to do.

A. have?????? B. to have????? C. has???????? D. having

The human body has hundreds of muscles. The three types are skeletal(骨骼的) muscles, smooth muscles and cardiac, or heart muscles. Each kind of muscle has a special job to do. 

The skeletal muscles are attached to the bones; they actually hold the skeleton together. Strong cords, called tendons(肌腱), help connect these muscles to the bones. Skeletal muscles give us strength and allow us to move in many ways. If you look at skeletal muscles through a microscope, you will see that it has bands of fibers that look like stripes(条纹). These stripes are called striations. Skeletal muscles usually move because the brain has sent a conscious message to them telling them what to do. This is called voluntary movement.

Another type of muscle is smooth muscle. Unlike skeletal muscle, smooth muscle does not have striations. This is found in organs such as the stomach, the bladder(膀胱), the lungs and the eyes. Smooth muscles are smaller than the skeletal muscles and they move involuntarily. The brain tells these muscles what to do, but we aren’t even aware of it. For example, we don’t have to think about breathing or digesting food. The smooth muscles just do their jobs automatically. For this reason smooth muscles are sometimes called involuntary muscles.

Like smooth muscle, cardiac muscle also works involuntarily. It is a very thick muscle that is found only in the walls of the heart. Its job is to pump blood out of the heart and into blood vessels called arteries(动脉). The arteries help carry the blood to all parts of the body. When the cardiac muscles relax, they let blood back into the heart. Cardiac muscles have striations, just like skeletal muscles do.

1.When we _______, the job is done by smooth muscles.

A．close our eyes      B．kick a ball          C．hug our friends     D．lift a suitcase

2.Skeletal muscles and heart muscles are alike because_______.

A．both can move voluntarily

B．both are thick muscles

C．both are bigger than smooth muscles

D．both have stripes called striations

3.Which of the following is TRUE according to the passage?

A．Heart muscles are very important because they give us strength and allow us to move.

B．The heart of human beings completely consists of heart muscle.

C．The skeletal muscles are connected to the bones by tendons.

D．Smooth muscle does its work without receiving message from the brain.

The human body consists of organs, each ____a definite job to do.