点A为数轴上表示－2的动点，当点A沿数轴移动4个单位长度到点B时，点B所表示的数为(     )

阅读理解

    People in the western state of California who are in the United States illegally can now request a driver's license. The law went into effect on January l. California is not the first American state with such a law, but it has the largest number of illegal immigrants. More than a million people began to request licenses shortly after the new state law went into effect. Among them was Christian Alvarado. Mr. Alvarado entered the United States from El Salvador eight years ago without permission from the U.S. government. Some call such people "illegal immigrants." Others call them "undocumented immigrants".

    Mr. Alvarado thinks it so exciting, for he has been waiting for the license for a long time. But some are worried that their personal information will be used to find them and deport them. Armando Botello is a spokesman for the California Department of Motor Vehicles, or DMV. He says people should not be afraid, for such information will not be shared.

    The new licenses are the same as licenses given to citizens except that they have the words "Federal Limits Apply". That means the license cannot be used to travel on an airplane or enter a federal building. Ana Garcia, working at the Central American Resource Center, says some illegal immigrants fear those words will be used to abuse them. Civil rights groups say the police and others will not.

    Dan Schnur, a political scientist at the University of Southern California, said that the main argument against the new law is that it rewards illegal behavior. But Professor Schnur argued that young, white Americans generally support immigration reform, including giving driver's licenses to illegal immigrants

    "It's simply because they grew up in a much more multicultural society than their parents or their grandparents did." Professor Schnur says he believes the changes in beliefs about illegal immigrants that have taken place in California will spread throughout the United States.

绿萝属于半阴生藤蔓植物，喜湿润环境．下图为一株绿萝植物被放置于黑暗中3d，标号A至E的5张大小相同的叶片被取下置于黑暗中进行实验．请分析回答：

（1）从图中可得出的结论是（写出2条）：　____ 

（2）有同学想证明这种植物上表皮的气孔少于下表皮，于是将E叶片叶柄去掉并用胶带纸封口，将上表皮朝下放在5%蔗糖溶液中，下表皮朝上不接触蔗糖溶液．2d后脱色并用碘液处理．

实验假设是：____．

预期实验现象是：____ ．

（3）研究发现，当土壤干旱时，绿萝根细胞会迅速合成某种化学物质x．有人推测根部合成X运输到叶片，能调节气孔的开闭．他们做了如下实验：从同一植株上剪取大小和生理状态一致的3片绿萝叶，分别将叶柄下部浸在不同浓度X的培养液中．一段时间后，测得的有关数据如下表所示：（注：气孔导度越大，气孔开启程度越大）

①以上方案有两处不完善的地方，请指出来并加以修正．

a．____ ．

b．____ ．

②叶片的蒸腾速率可反映气孔的开放程度，若表中数据为方案完善后得到的结果，那么可推测，随着培养液中X的浓度增大，叶片蒸腾作用强度____