5月14日，2017年一带一路高峰论坛于北京举行。3年多来，“一带一路”建设从无到有、由点及面，进度和成果超出预期。取得以上成就,最根本的一条是（    ）

在△ABC中，a，b，c分别为内角A，B，C的对边，3cosA﹣cos（B+C）=1，a=$\sqrt{15}$，B=$\frac{\mathrm{\pi }}{4}$，则b等于（　　）

读图回答下题

你认为下面两句广告语有什么语病?请改一改。

①今年过节不收礼，收礼还收脑白金。

②艾儿洗面奶特别适合任何肌肤。

    Only two countries in the advanced world provide no guarantee for paid leave from work to care for a newborn child. Last spring one of the two, Australia, gave up the bad distinction by setting up paid family leave starting in 2011. I wasn't surprised when this didn't make the news here in the United States — we're now the only wealthy country without such a policy.

    The United States does have one explicit family policy, the Family and Medical Leave Act, passed in 1993. It entitles workers to as much as 12 weeks' unpaid leave for care of a newborn or dealing with a family medical problem. Despite the modesty of the benefit, the Chamber of Commerce and other business groups fought it bitterly, describing it as “government-run personnel management” and a “dangerous precedent (先例).” In fact, every step of the way, as (usually) Democratic leaders have tried to introduce work-family balance measures into the law, business groups have been strongly opposed.

    As Yale law professor Anne Alstott argues, justifying parental support depends on defining(定义) the family as a social good that, in some sense, society must pay for. Parents are burdened in many ways in their lives: there is “no exit” when it comes to children. Society expects — and needs — parents to provide their children with continuity of care. And society expects — and needs — parents to persist in their roles for 18 years, or longer if needed.

    While most parents do this out of love, there are public punishments for not providing care. What parents do, in other words, is of deep concern to the state, for the obvious reason that caring for children is not only morally urgent but important to the future of society. To classify parenting as a personal choice for which there is no collective responsibility is not merely to ignore the social benefits of good parenting; really, it is to steal those benefits because they accrue (累积) to the whole of society as today's children become tomorrow's citizens. In fact, by some estimates, the value of parental investments in children, investments of time and money, is equal to 20-30% of GDP. If these investments bring huge social benefits — as they clearly do — the benefits of providing more social support for the family should be that much clearer.