有效氧化钙与氧化镁含量是判定石灰质量的主要指标。 ( )

水土流失是指因地面坡度大，降雨不能就地消纳。水往低处流，冲刷土壤，导致水分和土壤一起流失的现象。（）

甲乙分别在山上伐木，为图方便，各自将伐下的原木从山上滚下，不料其中一根木头砸伤了山下的行人丙，且无法确定是谁推下的这根木头，丙的损害应由（）

A、甲乙承担按份责任

B、甲乙承担连带责任

C、甲乙丙分担

D、丙自己承担

某企业只生产一种产品，该产品各项目占销售收入的百分比分别为：直接材料30%；直接人工15%；变动制造费用15%；变动管理费用7%；变动销售费用3%。该企业年度固定成本总额为150000元，产品销售单价为50元。所

得税率为33%。

[要求]

（1）计算单位产品制造边际贡献和单位产品边际贡献；

（2）计算变动成本率和边际贡献率；

（3）单位变动成本和单位边际贡献；

（4）计算该产品的盈亏临界点销售量和销售额；

（5）计算目标税后利润为140700的销售量。

Can you imagine how you would feel if you fell dangerously ill and could not reach or call a doctor Millions of people (1) the world are in this unfortunate (2) , living in distant places (3) there are no railways, no proper roads and no telephones. Thousands of (4) are lost every year (5) could have been saved if medical attention (6) in time. (7) today help could be brought quickly and easily (8) many of these people (9) full advantage was taken (10) the aeroplane. (11) country has proved this (12) than Australia. The Australians (13) greater use of the aeroplane than any (14) people in the world. In no other country (15) the total number of miles flown by the (16) person so high. In fact, it has been (17) that Australians jump into planes (18) people in other countries jump into trains and buses. It is not surprising, (19) that Australia should have been the first country (20) a Flying Doctor Service.

A．people

B．children

C．lives

D．families

根据《基于SDH的多业务传输节点（MSTP）本地光缆传输工程验收规范》，传输机房应安装（）V交流插座。

A.380

B.220

C.180

D.54