题目内容
（请给出正确答案）
简答题官方参考答案
（由简答题聘请的专业题库老师提供的解答）
更多“Electronic mail is the most effective way to send messages, assignment feedback, and other targeted”相关的问题
A、一阶导数等于零，二阶导数小于零； The first derivative is zero, the second derivative is less than zero;
B、一阶导数等于零，二阶导数大于零； The first derivative is zero, the second derivative is greater than zero;
C、一阶导数等于零，二阶导数等于零； The first derivative is zero, the second derivative is zero;
D、一阶导数等于零; The first derivative is zero;
A、-20 V
B、-2 V
C、-0.2 V
D、0.02 V
B．Although positive feedback loops are probably the most prevalent way of ensuring that daughter cells remember what kind of cells they are meant to be,there are other ways of reinforcing cell identity. One involves the methylation of DNA．In vertebrate cells, DNA methylation occurs on certain cytosine bases. This covalent modification generally turns off the affected genes by attracting proteins that bind to methylated cytosines and block gene transcription. DNA methylation patterns are passed on to progeny cells by the action of an enzyme that copies the methylation pattern on the parent DNA strand to the daughter DNA strand as it is synthesizeD
C．Another mechanism for inheriting gene expression patterns involves the modification of histones. When a cell replicates its DNA,each daughter double helix receives half of its parent’s histone proteins, which contain the covalent modifications that were present on the parent chromosom
E．Enzymes responsible for these modifications may bind to the parental histones and confer the same modifications to the new histones nearby. It has been proposed that this cycle of modification helps reestablish. the pattern of chromatin structure found in the parent chromosome
D．Because all of these cell-memory mechanisms transmit patterns of gene expression from parent to daughter cell without altering the actual nucleotide sequence of the DNA,they are considered to be forms of epigenetic inheritanc
E．These mechanisms, which work together, play an important part in maintaining patterns of gene expression, allowing transient signals from the environment to be remembered by our cells—a fact that has important implications for understanding how cells operate and how they malfunction in diseas
E．
●Extreme Programming (XP) is a discipline ofsoftware development with__(71) of simplicity, communication, feedback and courage. Successful software development is a team effort - not just the development team, but the larger team consisting of customer, management and developers. XP is a simple process that brings these people together and helps them to succeed together. XP is aimed primarily at object-oriented projects using teams of a dozen or fewer programmers in one location. The principles of XP apply to any (72) project that needs to deliver quality software rapidly and flexibly.
An XP project needs a (73) customer to provide guidance. Customers, programmers, managers, are all working (74) to build the system that's needed. Customers - those who have software that needs to be developed - will learn simple, effective ways to (75)what they need, to be sure that they are getting what they need, and to steer the project to success.
(71)
A.importance
B.keys
C.roles
D.values
(72)
A. small-sized
B.moderately-sized
C. large-sized
D.huge-sized
(73)
A.part-time
B.casual
C.seldom
D.full-time
(74)
A.together
B.by themselves
C.separately
D.alone
(75)
A. tell
B.know
C.communicate
D.feedback
警告：系统检测到您的账号存在安全风险
为了保护您的账号安全，请在“简答题”公众号进行验证，点击“官网服务”-“账号验证”后输入验证码“”完成验证，验证成功后方可继续查看答案！
