动量矩定理成立的条件是____________。

案例分析 Directions: In this section you are supposed to analyze the following cases from the perspective of intercultural communication. Then write an analysis about 100 words on the cultural differences and cultural understanding in the case. Crossing cultures for business can be frustrating when it interferes with getting the job done. Most Americans are very time sensitive when it comes to meetings and deadlines. If the meeting was to commence at 2:00, then all parties are to be present at that time. While the Chinese do not view time as an absolute but more as a suggestion. Concern is not expressed for a meeting starting late or ending at a different time. The same can be applied to deadlines. If a report is due on Friday, an American would be waiting for that report to be received before the end of business day while the Chinese would not worry if it showed up several days later.

A、直摆腿勾脚尖

B、直摆腿屈膝

C、摆腿至腰部

D、击掌与拍脚两响连贯

A、分部分项工程费

B、措施项目费

C、其他项目费

D、规费及税金

A、半工

B、单工

C、半双工

D、双工

A、先增大后下降

B、先下降后增大

C、持续下降

D、持续增大

声波检测法Acoustic detection 原理：物体间相互碰撞均会产生振动，发出声音，形成声波How it works： objects collide with each other and vibrate, producing sound and sound waves 管道发生破裂时产生的声波沿着管道内流体向管道上下游高速传播，安装在管段两端的声波传感器监听并将捕捉到声波波形，并与计算机数据库中的模型比较，确定管道是否发生了泄漏及泄漏量等数值，同时根据管道在两端捕捉到的泄漏信号的时间差计算得到泄漏位置。 Pipeline fracture when the acoustic fluid along the pipe to pipe upstream and downstream high-speed transmission, installed on both ends of pipe section of acoustic sensors to monitor and capture the acoustic waveform, and compared with computer in the database model, to determine whether pipeline leakage and the leakage happened such as value, at the same time, according to the pipeline at both ends of leakage signal capture time calculated leakage location. 优点：可实现连续的在线检测，并且能检测到很小的泄漏量，具有很好的灵敏性，误报率低，定位精度高，适应性好，安装费用和维护费用也较低。Advantages： it can realize continuous online detection, and can detect a small amount of leakage, with good sensitivity, low false alarm rate, high positioning accuracy, good adaptability, installation and maintenance costs are also low.

A、筛板塔

B、填料塔

C、不带搅拌的混合澄清器

D、转盘萃取塔