下列选项中是（）衡量计算机性能指标之一。A、CPU主频 B、光驱速率 C、显示器大小 D、

如图9-5-5所示，物体静止于水平地面上的O点，弹簧水平原长为L₀，物体的质量为m，它与地面间的动摩擦因数为μ，现将物体向右拉一段位移，放手使之在一段时间内来回振动，最后停止.弹簧劲度系数为k，则（   ）

图9-5-5

A．物体经过O点时受的合力为零

B．物体向左移，通过O点左边某点，使弹簧压缩ΔL时，物体受的合力大小为μmg+kΔL

C．物体最后可能静止在O点

D．物体受的摩擦力一定等于μmg

根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。

Secret codes (密码)keep messages private。Banks, companies, and government agencies use secret codes in doing business, especially when information is sent by computer.

People have used secret codes for thousands of years. 36 Code breaking never lags(落后) far behind code making. The science of creating and reading coded messages is called cryptography.

There are three main types of cryptography. 37 For example, the first letters of “My elephant eats too many eels” Spell out the hidden message “Meet me.”  

38 You might represent each letter with a number, For example, Let’s number the letters of the alphabet, in order, from 1 to 26. If we substitute a number for each letter, the message “Meet me” would read “13 5 20 13 5.”

A code uses symbols to replace words, phrases, or sentences. To read the message of a real code, you must have a code book. 39 For example, ”bridge“ might stand for “meet” and “out” might stand for “me.” The message “bridge out” would actually mean “Meet me.” 40 However, it is also hard to keep a code book secret for long. So codes must be changed frequently.

37（）

A. It is very hard to break a code without the code book.

B. In any language, some letters are used more than others.

C. Only people who know the keyword can read the message.

D. As long as there have been codes, people have tried to break them.

E. You can hide a message by having the first letters of each word spell it out.

F. With a code book, you might write down words that would stand for other words.

G. Another way to hide a message is to use symbols to stand for specific letters of the alphabet.

物流运输业的产品是（）属于（）即服务业。

抹灰按所用材料不同有哪些分类

Y公司系ABC会计师事务所常年的审计客户，2009年度在经营形势、内部管理等方面与2008年度比较未发生重大变化，未发生重大重组行为。A注册会计师作为2009年度财务报表审计的审计负责人，在复核销售与收款审计工作底稿时注意到以下问题，请代为作出正确的专业判断。

Y公司2009年12月20日记录的一笔大额营业收入，经审查原始凭证发现，发票开具日期为12月20日，出库单和发运凭证均在2010年1月20日，但货款已收到。对此A注册会计师询问了有关人员，得到的答复是，按合同应于12月发货，但因某些特殊情况将发货日推迟到1月20日。下面是A注册会计师可能采取的措施，你认为正确的是( )。

A．可以确认收入，无需进行调整

B．不能确认收入，应以发货日期为收入的确认日

C．应实施追加审计程序，以得到进一步的证实

D．如果Y公司不作适当的调整，由于金额重大，出具保留意见的审计报告