用肉眼直接观察发现材料偏在物镜的右下方，通过目镜观察发现物像偏在视野的右下方时，

水鸡声

在1mol/L的HAc溶液中，欲使H+浓度增大，可采取下列何种方法（）。

A.加水；

B.加NaAc；

C.加NaOH；

D.加0.1mol/LHCl溶液

Recent years have brought minority-owned businesses in the United States unprecedented opportunities--as well as new and significant risks. Civil right activists have long argued that one of the principal reasons why Blacks, Hispanics and other minority groups have difficulty establishing themselves in business is that they lack of access to the sizable orders and subcontracts that are generated by large companies. Now Congress, in apparent agreement, has required by law that businesses awarded federal contracts of more than ＄500,000 do their best to find minority subcontractors and record their efforts to do so on forms filed with the government. Indeed, some federal and local agencies have gone so far as to set specific percentage goals for apportioning parts of public works contracts to minority enterprises.

Corporate response appears to have been substantial. According to figures collected in 1977, the total of corporate contracts with minority businesses rose from ＄77 million in 1972 to 1.1 billion in 1977. The projected total of corporate contracts with minority businesses for the early 1980’s is estimated to be over ＄ 3 billion per year with no letup anticipated in the next decade.

Promising as it is for minority businesses, this increased patronage poses dangers for them, too. First, minority firms risk expanding too fast and overextending themselves financially, since most are small concerns and, unlike large businesses, they often need to make substantial investment in new plants, staff, equipment and the like in order to perform work subcontracted to them. If, thereafter, their subcontracts are for some reason reduced, such firms can face potentially crippling fixed expenses. The world of corporate purchasing can be frustrating for small entrepreneurs who get requests for elaborate formal estimates and bids. Both consume valuable time and resources, and a small company’s efforts must soon result in orders, or both the morale and the financial health of the business will suffer.

A second risk is that White-owned companies may seek to cash in on the increasing apportionment through formation of joint ventures with minority-owned concerns. Of course, in many instances there are legitimate reasons for joint ventures; clearly, White and minority enterprises can team up to acquire business that neither could acquire alone. But civil right groups and minority business owners have complained to Congress about minorities being set up as "fronts" with White backing, rather than being accepted as full partners in legitimate joint ventures.

Third, a minority enterprise that secures the business of one large corporate customer often runs the danger of becoming and remaining dependent. Even in the best of circumstances, fierce competition from larger, more established companies makes it difficult for small concerns to broaden their customer bases; when such firms have nearly guaranteed orders from a single corporate benefactor, they may truly have to struggle against complacency arising from their current success. (469 words)

Notes: civil rights activists 公民权利激进分子。Hispanics 西班牙后裔美国人。sizable orders 大额订单。subcontract 转包合同。on forms filed with the government 在政府存档备案。percentage goals 指标。apportionment 分配，分派。public works 市政工程。letup 减弱，缓和。promising as it is...这是as引导的让步状语从句，表语倒装了。patronage 优惠。concern n.公司。and the like 以及诸如此类的。crippling fixed expenses 引起损失的固定开支。the world of 大量的。bid 投标。to cash in on...靠……赚钱。team up 一起工作，合作。"fronts" 在此处意为“摆门面”。complacency 自满。

The primary purpose of the text is to（）

A. present a commonplace idea and its inaccuracies

B. describe a situation and its potential drawbacks

C. propose a temporary solution to a problem

D. analyze a frequent source of disagreement

下列关于愈伤组织的说法中不正确的是（）

A.愈伤组织的细胞能够进行细胞分裂

B.人们可以从愈伤组织中提取所需物质

C.用叶培养形成的愈伤组织细胞能够进行光合作用

D.愈伤组织的每一个细胞仍然具有发育的全能性

什么是精制有机肥？