搜题请搜索小程序“爱下问搜题”
问题 填空题

在中考期间，考场周边有“禁鸣喇叭、缓行，谢谢合作”的提示牌，噪声是由发声体的______振动产生的，“禁鸣喇叭”的提示是在______处减弱噪声．

答案

从物理学角度来说，噪声是发声体无规则振动产生的，“禁鸣喇叭”是在声源处减弱噪声的．

故答案为：无规则；声源．

单项选择题

There is nothing in this world constant but inconstancy. —SWIFT Project after project designs a set of algorithms and then plunges into construction of customer-deliverable software on a schedule that demands delivery of the first thing built. In most projects, the first system built is 1. ______ usable. It may be too slow, too big, awkward to use, or all three. There is no 2.______ but to start again, smarting but smarter, and build a redesigned version in which these problems are solved. The discard and 3.______ may be done in one lump, or it may be done piece-by-piece. But all large-system experience shows that it will be done. Where a new system concept or new technology is used, one has to build a system to throw away, for even the best planning is not so omniscient (全知的) as to get it right the first time. The management question, therefore, is not whether to build a pilot system and throw it away. You will do that. The only question is whether to plan in advance to build a 4.______, or to promise to deliver the throwaway to customers. Seen this way, the answer is much clearer. Delivering that throwaway to customers buys time, but it does SO only at the 5.______ of agony (极大痛苦) for the user, distraction for the builders while they do the redesign, and a bad reputation for the product that the best redesign will find hard to live down. Hence plan to throw one away; you will, anyhow.

5.（）

A．worth

B．value

C．cost

D．invaluable
查看答案
单项选择题

液化石油气的热值是城市煤气的（）倍。

A、5

B、6

C、7

D、8
查看答案