如下图，收集一试管CO2气体，然后倒插入盛澄清石灰水的烧杯中，你会观察到什么现象

2012年春节期间，小黄和父母选择了标价为2 680元／人云南五日游，小黄在腾冲的地摊上花50元买了几件富有数民族特色的小饰品，父母则在“ * * 云南”商场用刷贷记消费的方式购买了8 000元的玉镯。在这里涉及的货币职依次是

A．价值尺度、支付手段、流通手段

B．支付手段、流通手段、价值尺度

C．支付手段、价值尺度、流通手段

D．价值尺度、流通手段、支付手段

如图是植物细胞和动物细胞的立体结构，请据图回答问题．

（1）如图，代表动物细胞的是　 　图．

（2）甲图中①所示结构是　 　，其中的细胞液溶解着多种物质．

（3）甲图中⑥所示结构是　  　，对细胞起保护和支持作用．

（4）植物、动物细胞都具有的结构是②　  　、③细胞质、④　  　、⑤细胞膜．

安全管理基本原理包括（）。

A.系统原理

B.人本原理

C.预防原理

D.能量原理

E.效益原理

某桥梁工程，其基础为钻孔桩。该工程的施工任务由甲公司总承包，其中桩基础施工分包给乙公司，建设单位委托丙公司监理，丙公司任命的总监理工程师具有多年桥梁设计工作经验。
施工前甲公司复核了该工程的原始基准点、基准线和测量控制点，并经专业监理工程师审核批准。
该桥1号桥墩桩基础施工完毕后，设计单位发现：整体桩位(桩的中心线)沿桥梁中线偏移，偏移量超出规范允许的偏差。经检查发现，造成桩偏移的原因是桩位施工图尺寸与总平面图尺寸不一致。因此，甲公司向项目监理机构报送了处理方案，要点如下：
1．补桩；
2．承台的结构钢筋适当调整，外形尺寸做部分改动。
总监理工程师根据自己多年的桥梁设计工作经验，认为甲公司的处理方案可行，因此予以批准。乙公司随即提出索赔意向通知，并在补桩施工完成后第5天向项目监理机构提交了索赔报告：
1．要求赔偿整改期间机械、人员的窝工损失；
2．增加的补桩应予以计量、支付。
理由是：
1．甲公司负责桩位测量放线，乙公司按给定的桩位负责施工，桩体没有质量问题；
2．桩位施工放线成果已由现场监理工程师签认。
问题

总监理工程师批准上述处理方案，在工作程序方面是否妥当，说明理由。简述监理工程师处理施工过程中工程质量问题工作程序的要点。

Immigrants are consumers as well as producers, so they create jobs as well as taking them. And the work they do need not be at the expense of native workers. Immigrants often hold jobs that natives are unwilling to accept at any feasible wage.

Also, immigrants sometimes help to keep industries viable (能存活的) that would otherwise disappear altogether, causing employment to fall. This was the conclusion of a study of the Los Angeles garment industry in the 1970s and 1980s. And when immigrants working for low wages do put downward pressure on natives’ wages, they may raise the (real) wages of natives in general by keeping prices lower than they otherwise would be.

In theory, then, the net effect of immigration on native wages is uncertain. Unfortunately, most of the empirical (经验主义的) research on whether immigrants make natives worse off in practice is also inconclusive except the effect, one way or the other, seems small. Most of this research has been done in America: if there were any marked influence on wages, that is where you would expect to find it, given the scale of immigration and the tendency of the newcomers to concentrate in certain areas. But most studies have compared wages and employment in areas with many immigrants to wages and employment in areas with few. For instance, one examined the impact of sudden and notorious inflow of refugees to Miami from the Cuban port of Mariel in 1980. Within the space of a few months, 125000 people had arrived, increasing Miami’s labor force by 7%. Yet the study concluded that wages and employment among the city’s natives, including the unskilled, were virtually unaffected. Another study examined the effect of immigration on wages and employment of those at the bottom of the jobs ladder-unskilled blacks and Hispanics. It found that a doubling of the rate of immigration had no detectable effect on natives.

The most recent work, admittedly, has tended to question these findings. Using more detailed statistics and more sophisticated methods than the earlier studies, this work has tended to find that immigrants’ wages take longer to rise to the level of the natives’ wages than has been supposed. This implies a more persistent downward pressure on the host economy’s labor market.

Typically these studies find that immigration does depress unskilled natives’ wages to a small extent. But nearly all economists would agree that the effects of immigration are insignificant in relation to other influences.

The passage is intended to convey that the effect of immigration on natives’ wages is ().

A. uncertain

B. persistent

C. inconclusive

D. insignificant