B．Having a low opinion of it.

　　C．Attaching no importance to it.

　　D．Adding supportive evidence to it.

　　解析　B　词义猜测题。根据画线处上一句可知，研究的过程比较困难，多次尝试均以失败告终，所以许多科学家对这一实验理念并不看好。have a low opinion of不看好......，故选B项。

　　3．What is the scientists' purpose to clone these monkeys?

　　A．To help with the study of human diseases.

　　B．To serve as a stepping stone to their reputation.

　　C．To prepare for their research on human cloning.

　　D．To raise money for holding an exhibition of novels.

　　解析　A　细节理解题。根据第三段第四句可知，科学家们克隆这些猴子的目的是帮助研究人类疾病，故选A项。

　　4．What can we infer from the passage?

　　A．New techniques seem to be pointless.

　　B．Cloning humans is already on its way.

　　C．Society won't agree to clone another monkey.

　　D．Cloning monkeys has made contributions to certain scientific areas.

　　解析　D　推理判断题。根据第三段最后一句可知，成功克隆猴子为研究人类生物学和疾病提供了新的范例；由此可推知，成功克隆猴子已经为某些科学领域作出了贡献，故选D项。

　　B

课标话题 人与自然·自然科学研究成果 体裁 说明文 词　　数 346 难度 　　(2019·郑州一中摸底)Running is often tiring and a lot of hard work, but nothing beats the feeling you get after finishing a long workout around the track.

　　But while it's long been believed that endorphins(内啡呔)-chemicals in the body that cause happiness-are behind the so－called "runner's high"， a study suggested that there may be more to this phenomenon than we previously knew.

　　According to a recent study published by a group of scientists from several German universities, a group of chemicals called endocannabinoids(内源性大麻素) may actually be responsible for this familiar great feeling.

　　To test this theory, the scientists turned to mice.

　　Both mice and humans release high levels of endorphins and endocannabinoids after exercise, along with many other chemicals. After exercising on running wheels, the mice seemed happy and relaxed and displayed no signs of anxiety.

But after being given a drug to block their endorphins they changed. However, when their endocannabinoids were block with a different drug, the runner's high symptoms seemed to fade.