Lead deposits, which accumulated in
soil and snow during the 1960’s and 1970’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 world-wide 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 A. lead deposits in arctic snow are on the increase B. the Clean Air Act has not produced the desired results C. the US is the major source of lead pollution in arctic snow D. lead will stay in soil and snow longer than expected [多选题]《女神》的思想内容有( )
A.强烈的个性解放要求 B.强烈的反抗、叛逆与创造精神 C.炽热的爱国情思 D.青春、爱情的欢唱 E.大自然神奇力量的否定 [单选题]还原糖是指具有还原性的糖类。其糖分子中含有游离的()和游离的酮基
A.醛基 B.氨基 C.羧基 D.醇基 [单选题]( )Q235属于_____钢。
A.普通碳素 B.碳素工具 C.合金钢 D.弹簧钢 [单项选择]根据我国现行规定,关于预备费的说法中,正确的是()。
A. 基本预备费以工程费用为计算基数 B. 实行工程保险的工程项目,基本预备费应适当降低 C. 涨价预备费以工程费用和工程建设其他费用之和为计算基数 D. 涨价预备费不包括利率、汇率调整增加的费用 [单项选择]对安泰酮的描述,下列正确的是()
A. 主要是胆系排泄 B. 心功能不全、肝功能受损时应慎用或禁用 C. 镇痛作用完善 D. 可使周围血管收缩,中心静脉压上升 E. 过敏反应的发生率低于硫喷妥钠 [简答题]哪些车辆不得上高速公路行驶?
[简答题]HXD1C型电力机车辅助电气系统由___、AC220V电路、DC110V电源及其它电路组成。
[单选题]作为一种现象,城市垃圾问题早已凸显,异地倾倒、________,不过是垃圾困境的一种不当突围方式而已。治理垃圾异地倾倒问题,必须依靠严厉执法和监督举报,但最终还是要回到城市垃圾处理上来。
填入划横线部分最恰当的一项是:
A.投机取巧 B.以邻为壑 C.落井下石 D.寡廉鲜耻 [单选题]( )是消防救援人员行进的常用步法。
A.齐步 B.便步 C.正步 D.跑步 [多选题]在对站所终端(DTU)三遥进行配电自动化终端供货前接口检查时,应包含以下哪些项(____)
A.采集不少于4个母线电压和2个零序电压。每回路至少采集3个电流量。 B.采集不少于2路直流量,不少于20个遥信量,遥信电源电压不低于DC24V。 C.不少于4路开关的分、合闸控制。具备不少于4个可复用的RS232/RS485串行口和2个以太网通信接口。 D.采集不少于6个母线电压和2个零序电压。每回路至少采集5个电流量。 我来回答: 提交
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