问题 选择题

下列物质放入(或通入)水里,能形成溶液的是      

A.植物油

B.碳酸钙

C.氮气

D.食盐

答案

答案:D

题目分析:溶液的本质特征是均一性、稳定性,属于混合物;食盐易溶于水,能和水形成均一、稳定的混合物,即能和水形成溶液;植物油、碳酸钙、氮气都不溶于水,故不能和水形成溶液。故选D

点评:解答本题要分析物质的水溶性,如果物质易溶于水,就能够和水形成溶液,如果物质不溶于水,就不能够和水形成溶液。

问答题
单项选择题

Work looks a better cure for poverty than welfare Especially as fewer and fewer countries will be able to afford to pay potential workers to stay at home a Victorian idea is back in favour: many poor people are better off when they are pulled back into the labour market. The idea revived first in the United States. There, in its harshest form, the unemployed work in exchange for welfare. But countries with governments to the left of America’s, including Labour Australia and Socialist France, are now also exploring ways to link income support and employment policy.

Coming from different directions, the right and the left are gradually finding new common ground. For the right, it seems deplorable to encourage the poor to rely on the state for cash, because they get hooked on government help and accustomed to being poor. For the left, it seems deplorable to allow workers to drop out of the job market for long periods, because it makes it harder for them to find new jobs. For both, the answer is to get the poor to work.

Most industrial countries have a two-tier system of social protection: a social-security scheme, where workers and their bosses make regular contributions in exchange for payments to workers when they are unemployed, sick or retired; and a safety-net, to give some income to those poor people who have exhausted their social insurance or who have none The former is usually not means-tested but, for the unemployed, is of limited duration; the latter is almost always tied to income The public tends to approve of contributory benefits, which is what designers of such schemes intended.

Safety-net benefits carry no such sense of entitlement, and are less popular. Yet they have grown more rapidly in large part because the 1980-82 recession increased the number of people of working age who had exhausted their right to contributory benefits. And an increasing proportion of the poor are people for whom the contributory systems were never designed: the young and lone mothers. In consequence, payments which carry a clear entitlement have become less significant, compared with those which appear to depend purely on state charity.

The rise in the bill for the unpopular kind of social protection comes at a time when governments want to curb state spending. It comes, too, at a time when many countries have done almost everything they can think of to protect the poor. A decade ago many on the left argued that poverty was usually caused by circumstances outside the control of the poor—a lack of jobs, disability, old age, racial discrimination, broken marriages. One way or another, governments have tried to tackle most of these problems. Still the poor remain.

A safety-net benefit system is one()

A. based on the recipient’s prior contributions

B. of limited duration

C. that depends on state charity

D. that pays according to the claimant’s social insurance