—Yes, I am.

衣服、餐具上的油污可以用加入洗涤剂的水洗掉，因为洗涤剂（）

五种短周期元素的某些性质如下表所示，有关说法正确的是（   ）

阅读《简爱》第三十七章选段，完成后面问题。

       “但我至少要选择﹣﹣我最爱的人。简，你愿意嫁给我吗？”“是的，先生。”

       “一个你得用手牵着他走的可怜的瞎子。”“是的，先生。”

       “一个比你大二十岁的残疾人，还得由你来伺侯。”“是的，先生”“真的吗，简？”“完全当真，先生。”

问题：文中的“先生”是谁？简爱怎么结识“先生”的？“先生”变成残疾人的原因是什么？

阅读理解

    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.