开展农产品价格鉴证的作用包括（）。 A.使农产品价值得到充分和合理的实现，保障农业生

检测点火正时的方法有哪几种？

唐某打算炒股，苦于资金不够向朋友贾某借了1万元，并将自家的一台笔记本电脑(价值15000元)作为抵押。双方依法签订了借款合同和抵押合同，但没有办理抵押登记。唐某进入股市以后，股市逐渐低迷，唐某损失惨重。还款期限届至后，贾某向唐某索要借款，但唐某已经分文不剩，并且告知贾某，他的电脑已经以5000元的价格卖给宋某。贾某遂找到宋某，要求退还电脑抵偿债务。以下分析的正确的是：

A．抵押无效，贾某无权要求宋某返还电脑

B．抵押无效，但贾某有权要求宋某返还电脑

C．抵押有效，贾某有权要求宋某返还电脑

D．抵押有效，但贾某无权要求宋某返还电脑

接地体施工时，通常挖沟深度为（）。

A.0.5一0.7m

B.0.7m

C.`0.8一1.0m

D.1.2m

离心式鼓风机机壳的作用是：用来收集增压后的气体，并将其送入流道。

A conventional teacher’s licensee usually requires a university degree in education plus an unpaid term of practice teaching. This has never made much sense. It excludes bright students who take degrees in other subjects, and might teach those subjects; it is costly and time-consuming for career-switchers, who must wait a year or more before they can enter a classroom; it is so rigid that private-school teachers or university professors with years of experience have to jump through hoops before they can start teaching in a state school. And there is virtually no evidence that it creates better teachers. For all that, it is ply backed by schools of education, which have a monopoly of teacher-training, and by teachers’ unions, whose members make more money when it is artificially hard for others to get into the profession.

Now, some 45 states and the Districts of Columbia offer an "alternative route" to a teacher’s licensee, up from only a handful in the 1980s. Alternative certification (AC) generally allows individuals with a university degree to begin teaching immediately after passing an entrance examination. These recruits, watched over by a mentor teach the subject they studied at university, and take education courses at a sponsoring university while drawing their salaries.

The traditional sort of American teacher is likely to be young, white and female. Alternative certification attracts more men and more non-whites. In Texas, for instance, roughly 90% of public-school teachers are white, but 40% of those who have joined through alternative certification are non-whites. The AC route also draws teachers willing to go where they are most needed. A survey of Troops to Teachers, a program that turns exsoldiers into public-school teachers (" Proud to serve again"), found that 39% of those taking part are willing to teach in inner-city schools, and 68% in rural areas.

Are they good teachers Officialdom is reluctant to release the details which might answer that question for certain. But anecdotal evidence suggests they do well. In New Jersey, which has been running this sort of program since 1984, rich districts, which can afford to be choosy, consistently hire more AC teachers than poor districts do. In Houston, Texas, where the Teach of America program (TFA) puts recent university graduates into poor communities as teachers, the most effective teachers are generally the TFA ones. " School principals are our biggest fans," Wendy Kopp, TFA’s president, says proudly.

So why not scrap the cumbersome teacher-licensing laws Frederick Hess, a professor at the University of Virginia, has written a paper for the Progressive Policy Institute arguing that teacher-licensing ought to be stripped to the bare essentials. Prospective teachers should be required only to hold a college degree, pass a test of essential skills, and be checked to make sure they do not have a criminal background. Other training is important, argues Mr. Hess, but the market, not state legislators, should decide what that training looks like. This notion of "competitive certification" has drawn favorable attention from the Bush administration.

What does the example of New Jersey ( Para. 4) illustrate（）

A. Schools in rich districts are usually choosy

B. Official sources are careful on the success of AC

C. New Jersey has more need for teachers than elsewhere

D. AC has turned out good teachers for schools