听力原文：W: Everybody is talking about genes today, but do genes determine everything abou

M: (23) Genes and environment work together to shape who we are. As the environment includes everything we experience and come into contact with from birth through to death, it also plays an extremely complex role.

W: What is gene, then？

M: Even scientists disagree on exactly how to define a gene. Generally, a gene is a sequence of DNA that tells us what a single protein does. Proteins do the work of the body, building structure and stimulating biochemical reactions.

W: (24)How genetically similar are we to one another？

M: Individual humans are extremely similar to each other. They share 99.9 percent of their DNA no matter which race they belong to.

W: How genetically similar are we to other species？

M: Scientists have been amazed at how genetically similar humans are to other species. Humans share 80 percent of their genes with mice, about 99 percent of DNA with chimpanzees. That means that chimpanzees are more closely related to humans than to other animals, such as monkeys, whales or cats.

W: (25)Will genes lead to a cure for cancer and other serious disease？

M: Of course! Virtually every disease has genetic cause. Some are simple misspellings that can be corrected with gene therapy, although this technology is still in its infancy. Scientists will gain more knowledge about genes, and they will develop new treatments based on that knowledge. The outlook is especially good over the next few decades for some cancers and other disease.

(20)

A．Environment and genes.

B．Cells of proteins.

C．Genes of parents.

D．A sequence of DNA