在一个数的末尾添上2个0，这个数就扩大100倍。[ ]

若企业普通股股数为10000000股，流通在外的每股股价为20元，年盈利额为850万元，利润全部作为现金股利发放，则市盈率和股利收益率分别为（）。

A.23.54，7.08%

B.23.54，4.25%

C.14.12，7.08%

D.14.12，4.25%

免疫球蛋白的超变区位于（）。

A.VH和CH

B.VL和VH

C.FC段

D.VH和CL

E.CL和CH

2010年6月19日，甲公司主营销售电脑耗材，与乙公司签订借款合同。该借款合同约定：借款总额为2000万元，借款期限为3年，借款利率为4.5%，3年应付利息在借款之日预先一次从借款本金中扣除，借款期届满时一次全额归还所借款项，借款用于购买电脑耗材。任何一方违约，违约方应当向守约方按借款总额支付5%的违约金。乙公司要求甲公司提供担保，甲公司以正在建设中的办公楼作为抵押与乙公司签订了抵押合同，同时甲公司请求丙公司为保证人，并与乙公司签订了保证合同。乙公司与甲公司签订的抵押合同约定：如果甲公司不能按时偿还借款或不能承担违约责任，乙公司有权用抵押的房产变现受偿。乙公司与丙公司签订的保证合同约定：如果甲公司不能按时偿还借款或不能承担违约责任，而用甲公司抵押的正在建设中的办公楼变现受偿后仍不足以补偿乙公司的损失时，丙公司保证承担相应的补偿责任。
乙公司依照约定于2010年6月20日向甲公司交付借款，并从借款本金中扣除了3年的借款利息。2011年6月25日，乙公司证实甲公司将借款资金挪作他用，遂要求甲公司予以纠正，甲公司以借款资金应当由自己自行支配为由未予纠正。2011年7月10日，乙公司书面通知甲公司，要求甲公司提前偿还借款，甲公司以借款尚未到期为由拒绝偿还借款。2011年10月5日，乙公司向人民法院提起诉讼，要求解除借款合同，并要求甲公司提前偿还借款，将用于抵押的正在建设中的办公楼变现受偿，同时要求丙公司承担保证责任。经人民法院调查：甲公司实际投入购买电脑耗材的资金为1500万元，挪用资金500万元；正在建设中的办公楼经评估后的可变现价值为1200万元，但在抵押时未办理抵押登记；丙公司是甲公司控股的子公司，丙公司与乙公司签订保证合同时未获除甲公司之外的其他股东认可，并隐瞒了与甲公司的关联关系。
根据上述内容，分别回答下列问题：

乙公司与甲公司签订的抵押合同是否有效并说明理由。

Although man has known asbestos for many hundreds of years, it was not until 160 years ago that it was mined for the first time on the North American continent. H. W. Johns, owner of a New York City Supply Shop for roofers, was responsible for the opening of that first mine.

Mr. Johns was given a piece of asbestos which had been found in Italy. He experimented with the material and then showed its surprising powers to his customers. After putting on a pair of asbestos gloves, which looked much like ordinary work gloves, he took red-hot coals from the fireplace and played with them in his hands. How astonished the customers were to discover that he was not burned at all. You can well imagine that he had increasing business in asbestos roofing materials. However, because it was very expensive to transport (carry) them from Italy to the United States, Mr. Johns sent out a young scientist to seek a source nearer home. This young man found great vein, in the province of Quebec in Canada.

Ever since 1881 Quebec has led the world in the production of this unusual mineral, which is made up of magnesium, silicon, iron, and oxygen. When it is mined, the asbestos is heavy, just as you would expect a mineral to be. When it is separated, a strange thing happens: the rock breaks down into fine, soft, soapy fibres.

Scientists do not know why the rock can be separated easily into threads, but they have found thousands of uses of this fireproof material, of the so-called "cloth of stone".

Which is the most important character of asbestos that the author wants to show us（）

A. It is like thread.

B. It feels soapy.

C. It burns easily.

D. It is unusually heavy.

下列哪项是超声造影成像技术（）

A.触发成像技术

B.二次谐波成像技术

C.间断谐波成像技术

D.脉冲反向谐波成像技术

E.以上均是