受限空间与其他系统连通的可能危及安全作业的管道应采取有效隔离措施，管道安全隔绝措施应

牙本质暴露但未露髓的冠折牙，形成足够修复性牙本质的时间是（）。

A.冠折后1月

B.冠折后4～6周

C.冠折后6～8周

D.冠折后9～10周

E.冠折后8～9周

戴一头金黄色假发，穿一件白上衣的歌唱演员，在屋顶上挂一盏红色霓虹灯的大厅里演出，在这盏灯的照射下，我们会看到她戴的假发是______色，上衣是______色．

读我国某地区的等高线图，据图回答。

（1）该地区的盛行风是（　　）

A．东北风         B．西北风          C．东南风         D．西南风

（2）我国哪一地理区内，最可能有此种地形分布（　　）

A．云贵高原                     B．黄淮平原

C．珠江三角洲                D．塔里木盆地

（3）此种地形的分布区，其气候图最有可能是图中的（　　）

The following questions present a sentence, part of which or all of which is underlined. Beneath the sentence you will find five ways of phrasing the underlined part. The first of these repeats the original; the other four are different. If you think the original is best, choose the first answer; otherwise choose one of the others.

These questions test correctness and effectiveness of expression. In choosing your answer, follow the requirements of standard written English; that is, pay attention to grammar, choice of words, and sentence construction. Choose the answer that produces the most effective sentence; this answer should be clear and exact, without awkwardness, ambiguity, redundancy, or grammatical error.

While the new health insurance regulations may be onerous for large corporations, it can potentially be disastrous for small business owners, who in many cases will have to lay off employees in order to pay for the extended coverage.（）

A. it can potentially be disastrous for small business owners, who

B. they are potential disasters for small business owners, since

C. potentially they will be disastrous for small business owners, whom

D. for small business owners it is a potential disaster, because

E. they are potentially disastrous for small business owners, who

下列说法正确的是

A．糖类、油脂和蛋白质是基本营养物质，它们都是天然高分子化合物

B．蛋白质水解的最终产物是多肽

C．米酒变酸的过程涉及了氧化反应

D．向蛋白质溶液中加入浓的Na₂SO₄或CuSO₄溶液均可使蛋白质盐析而分离提纯