The city will later this year.

    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 percent of Europeans. The other is found in 93 to 100 percent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

    Scientists have changed the color of a dark-striped zebra-fish（斑马鱼） to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebra-fish 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 zebra-fish, 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 zebra-fish 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.

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注意：

1）词数100左右；

2）可以适当增加细节，使行文连贯。

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根据下面提示，以Healthy Diet为题写一篇100词左右的短文。

1). 健康饮食的重要性。

(1.) 有助于保持健康与正常体重；

(2.) 有助于保持体力，精力充沛地进行学习与劳动；

(3.) 有助于提高生活质量。

2). 什么是健康饮食？

(1.) 合理的饮食结构；

(2.) 绿色蔬菜与水果；

(3.) 愉快的心情、适量的体育锻炼与健康的饮食同等重要。

注意：1).词数100左右；

2).短文必须包括以上所有要点，可适当增加细节，以使行文连贯。

Healthy Diet

    It's of great importance for everyone to form a good habit of healthy diet.

The children couldn't every day.

—Of course I did. As a matter of fact,  I had such fun that time seemed to ______ so quickly.