[单选题]下列不属于碳素结构钢的是( )。
A.黑铁皮
B.白铁皮
C.马口铁
D.不锈钢

当前我国商业银行全面推行资产负债比例管理，并根据国际惯例和我国实际情况制定了资产负债比例管理指标体系，资本充足率是其中的主要指标，现假设我国某商业银行的有关数据如下：资本总额为3000万元，核心资本为2000万元，法定盈余公积金为600万元，附属资本为1000万元，对其他企业投资400万元，加权风险资产总额为40000万元。

Scientists are trying to make the deserts into good land again. They want to bring water to the deserts so people can live and grow good. They are learning a lot about the deserts. Even so, more and more of the earth is becoming desert all the time. Scientists may not be able to change the deserts in time.
Why is more and more land becoming desert Scientists think that people make deserts. People are doing bad things to the earth.
Some places on the earth do not get very much rain. Yet they still do not become deserts. This is because there are some green plants growing there. Small green plants and grass are very important to dry places. Plants help keep water in the earth. Plants do not let the wind blow the dirt away. Without plants, the land can become a desert much more easily.
A man decides to make a farm in a very dry place. He cuts down the trees. He digs in the earth and takes away the grass and plants that are already