读“塔里木盆地区域图”，回答1—3题。

1、楼兰古城在两千多年前曾是塞外水乡、林草繁茂的绿色王国和丝路重镇，但现在已经消失。楼兰古城消失的主要人为原因是[ ]

A．位于丝绸之路，战争频繁

B．位于大陆内部，降水稀少

C．灌溉用水过多，植被被破坏

D．风力大，风力侵蚀作用强

2、图中N为塔里木盆地的—内陆湖，M为湖边的—小绿洲，N湖的主要补给水源与M绿洲盐碱化最严重的季节分别是[ ]

A．地下水夏季

B．冰雪融水春季

C．冰雪融水夏季

D．地下水秋季

3、塔里木盆地的北部有炽热的阳光和洁净的空气，是世界上最适宜种植番茄的区域之一。下列关于该地区番茄与东北地区的番茄相比，正确的是[ ]

A．用水量大，单产低

B．主要分布在河谷地区

C．土壤贫瘠是制约因素

D．含糖量大，口感好

(66) is a one-way function that takes an arbitrarily long piece of plaintext and from it computes a fixed-length bit string. (67) is a protocol that most USENET machines how use it to allow news articles to propagate from one machine to another over a reliable connection. (68) is an approach preferred by cable TV providers. In this solution the fiber terminates at an optoelectrical converter and the final segment is a shared coaxial cable. (69) is a device used to connect two separate network that use different communication protocol. (70) js a digital-to-digital polar encoding method in which the signal level is always either positive or negative.

A．Router

B．Gateway

C．Bridge

D．hub