If you get lost, you should keep calm beca

下列代谢物经相应特异脱氢酶催化脱下的2H，不能经过NADH呼吸链氧化的是

A．异柠檬酸

B．苹果酸

C．α-酮戊二酸

D．琥珀酸

E．丙酮酸

大桥是指桥长（）以上至500m。

肠系膜上动脉一般与腹主动脉前壁呈一角度，正常不应超过（）。

A.90°

B.80°

C.60°

D.50°

E.30°

节段性室壁运动异常常见于（）

A.冠心病心绞痛

B.冠心病心肌梗死

C.心肌病

D.心肌炎

E.高血压性心脏病

In promising to fuse media as diverse as television, telephone communication, video games, music and data transmission, the era of digital convergence goes better than yesterday’s celebrated "information superhighway". Yet achieving this single technology is far from straightforward. There are currently three major television broadcast standards, and they are all incompatible with each other. But this is nothing compared to the many technologies supporting the Internet, each with a different bandwidth and physical media. The problems faced in designing platforms and communication systems that will be accepted across the world can appear insuperable.
Even once global standards are assured, however, a further obstacle lies in wait. The Internet is plagued by long, erratic response times because it is a pull-technology, driven by patterns of user demands. Push technology, on the other hand, reverses the relationship: servers simply send information to passive users, as in television and radio. But if some form of combination between one-way television flow and interactive Internet is to be the basis of our future media, it is hard to see how it could be operated. Moreover, the problem of fusing Internet with television is also one of defining the services offered. Information, entertainment and relaxation appear at first to be quite different needs. Serious doubts remain over whether consumers will be interested in having to make the sort of mental effort associated with computing while also settling down in front of a sitcom.
Besides the issue of consumer habits, infrastructure costs are set to be immense, and will have to be met by national states or the private sector before being passed on to users. Platforms do not necessarily have to be expensive. The mobile phone is a good example of how something that is technologically sophisticated can almost be given away, with its cost recovered through service charges. Users are then coerced through clever marketing to upgrade to newer phones with more features to reinforce their dependence.
Whatever the outcome, it is obvious that technology will play an increasing part in our everyday lives. Beyond technology, digital convergence embraces the services, industrial practices and social behavior that form modern society. We have in our hands the technology to construct the most sophisticated machines ever built, but if they are unusable, simply because of their operating instructions, then recent lessons have taught us they will not survive. Whatever we design must be simple, reliable and useful. Perhaps this is where artificial intelligence will come in.

In pointing out the problems faced in digital convergence, the author mainly employs the technique of______

A. cause and effect analysis.
B. argumentation and comments.
C. contrast and comparison.
D. enumeration and elaboration.