B. Up to now, seven kinds of animals have been cloned, including sheep, cats, humans and rabbits.

C. Professor Rudolf Jaenisch is carrying on an experiment on cloning an eight-week-old embryo.

D. Ronald Green doubts about the future successful birth of the so-called cloned embryo.

【解析】选D。细节理解题。根据第三段第一句话可知A项错误; 根据第三段第二句话可知B项错误; 根据第二段可知C项错误; 根据第五段最后一句话可知D项正确, 故选D。

4. Which is the best title for the passage?

A. The Success of Cloning Humans

B. The Anger at Cloning Humans

C. Failure of Cloning Humans

D. The First Cloned Human

【解析】选D。主旨大意题。综观全文可知文章讲的是科学家们对克隆人类的怀疑, 故选D。

Exercise is an important part of keeping a healthy lifestyle. Fitness tools and tips can help individuals develop an exercise plan that not only is safe but also helps them to work toward a certain goal such as weight loss or running a marathon.

Consult Your Doctor

Before beginning a weight loss or exercise program, it is best to consult(咨询)your doctor to make sure that you are in proper health and that there are no possible conditions that could get worse by exercise. Ask your doctor to recommend exercise based on your fitness level that will help you achieve your goals.

Set Goals and Limits

When beginning a fitness program, it is important to start off slow and work toward a more advanced goal. Begin with short 10-minute exercise each day to prepare your body for more active exercise and to prevent injury.

Drink Plenty of Water

During exercise, the body loses liquid from sweating, therefore, it is important to drink lots of water before, during and after exercising. Experts recommend drinking water or sports drinks every 15 to 20 minutes during exercise and more often during more active exercise. Continue to drink water several hours after exercising to refill liquid in the body.

Exercise Equipment

Exercise equipment such as treadmills(跑步机), exercise bikes and weights is a great way to stay fit when on a busy schedule or on rainy days. Before using exercise equipment at home or in the gym, educate yourself on the proper use of each piece to avoid injury to yourself or damage to the equipment.

Tracking Tools

Use of tools such as pedometers(计步器)or heart rate monitors can help record calories, steps and heart rate. These tools can help keep dieters and athletes active and eager to reach their health and fitness goals.