低钙血症最早期临床表现为A．手足抽搐 B．口周、指尖麻木感 C．腱反射亢进 D．肌肉

苯二氮卓类药物中毒，选用的解毒剂（）.

A．二巯基丁二钠 

B．亚甲蓝 

C．氯解磷定 

D．氟马西尼 

E．盐酸纳络酮

陈某将自己的轿车投保于保险公司。一日，其车被房东之子(未成年)损坏，花去修理费 1500元。陈遂与房东达成协议：房东免收陈某2个月房租1300元，陈不再要求房东赔偿修车费。后陈某将该次事故报保险公司要求索赔。在此情形下，以下哪一个判断是正确的

A．保险公司应赔偿1500元

B．保险公司应赔偿200元

C．保险公司应赔偿1300元

D．保险公司不再承担赔偿责任

ATM技术的特点是______。

A．网状拓扑
B．以信元为数据传输单位
C．以帧为数据传输单位
D．同步传输

Questions 21 to 25 are based on the following passage.

Lead deposits, which accumulated in soil and snow during the 1960’s and 70’s, were primarily the result of leaded gasoline emissions originating in the United States. In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation worldwide has decreased significantly.

A study published recently in the journal Nature shows that air-borne leaded gas emissions from the United States were the leading contributor to the high concentration of lead in the snow in Greenland. The new study is a result of the continued research led by Dr. Charles Boutron, an expert on the impact of heavy metals on the environment at the National Center for Scientific Research in France. A study by Dr. Boutron published in 1991 showed that lead levels in arctic (北极的) snow were declining.

In his new study, Dr. Boutron found the ratios of the different forms of lead in the leaded gasoline used in the United States were different from the ratios of European, Asian and Canadian gasolines and thus enabled scientists to differentiate (区分) the lead sources. The dominant lead ratio found in Greenland snow matched that found in gasoline from the United States.

In a study published in the journal Ambio, scientists found that lead levels in soil in the Northeastern United States had decreased markedly since the introduction of unleaded gasoline.

Many scientists had believed that the lead would stay in soil and snow for a longer period.

The authors of the Ambio study examined samples of the upper layers of soil taken from the same sites of 30 forest floors in New England, New York and Pennsylvania in 1980 and in 1990. The forest environment processed and redistributed the lead faster than the scientists had expected.

Scientists say both studies demonstrate that certain parts of the ecosystem (生态系统) respond rapidly to reductions in atmospheric pollution, but that these findings should not be used as a license to pollute.

It can be inferred from the last paragraph that scientists （）

A.are puzzled by the mystery of forest pollution

B.feel relieved by the use of unleaded gasoline

C.still consider lead pollution a problem

D.lack sufficient means to combat lead pollution

他认为在家里吃不如在饭馆儿吃干净。