题目内容：

Can people change their skin color without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin color.

    The gene comes in two versions, one of which is found in 99 per cent of Europeans. The other is found in 93 to 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

    Scientists have changed the color of a dark-striped zebrafish（斑马鱼） to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebrafish skin color is determined by pigment cells, which contain melanin (黑色素). The number, size and darkness of melanin per pigment cell determine skin color.

    It appears that, like the golden zebrafish, light-skinned Europeans also have a mutation (变异) in the gene for melanin production. This results in less pigmented skin.

    However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebrafish genes.

    Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun (太阳光紫外线), which can cause skin cancer.

    But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.

    Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin color, said Cheng.

    The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin color without damaging it like chemical treatment did on Michael Jackson.

1.The passage mainly tells us that ________.

A. people can not change their skin color without any pain

B. the new discovery could lead to research into ways to change skin color safely

C. pop king Michael Jackson often changed his skin color as he liked

D. scientists have found out that people’s skin color is determined by the gene

2.It can be inferred from the passage that ________.

A. nowadays people who want to change their skin color have to suffer a lot from the damage caused by the chemical treatment

B. Europeans and Africans have the same gene

C. the new discovery could help to find medical treatments for skin cancer

D. there are two kinds of genes

3.Scientists have done an experiment on a dark-striped zebrafish in order to ________.

A. find the different genes of humans’

B. prove the humans’ skin color is determined by the pigment gene

C. find out the reason why the Africans’ skin color is dark

D. find out the ways of changing people’s skin color

4.The reason why Europeans are light-skinned is probably that _____

A. they are born light-skinned people

B. light-skinned Europeans have mutation in the gene for melanin production

C. they have fewer activities outside

D. they pay much attention to protecting their skin

5.The writer’s attitude towards the discovery is ________.

A. neutral B. negative        C. positive       D. unconcerned