Mars has provoked much speculation on the possibilities of __1__life on Earth than any other planet in the Solar System. __2__The presence of water is a prerequisite for the existing of life. __3__Therefore, “follow the water” has been NASA’s chief guideline for the exploration of a red planet. Although Mars experiences __4__seasons like on Earth and as polar caps which composed __5__of carbon dioxide and water ice, today it is bone-dry and frigidly cold. But evidence is rapidly accumulating that Mars is once __6__much wetter, with a more clement climate.

　　This evidence comes from orbiting satellites and from data collected by roving landers.Since the 1970s, space probes of Mars have revealed __7__numerous features apparently craved by flowing water, such as winding, branched valleys resembling driedout streambeds and giant outflow channels gouged by catastrophic floods.Recent high-resolution imagery from the Mars Odyssey Themis reveal numerous examples of branched valleys that from __8__tightly-packed integrated drainage system. These channels

　origins at topographic high points; the valleys widen “downstream”, __9__some even displaying inner valleys. The valley networks densities,comparative to those of terrestrial drainage basins. __10__ These features were most likely produced by rainfall, during wetter, warmer periods in the past. 　

　　答案：

　　1、much—more 或much后加more 句法错误，后半部分出现了than，前半部分用比较级

　　2、on-beyond 词汇错误，“地球以外的生命”不因该用on。

　　3、existing—existence 此行混淆，“生命的存在”应用existence。

　　4、a-the

　　5、which去掉或which后加are，考试吧句法错误。

　　6、is-was 句法错误，时态错误。虽然主句的时态是现在进行时，但是从句中有时间状语once，所以用过去时。

　　7、of-to 词汇错误，probe与to，into搭配。

　　8、reveal-reveals 主谓不一致。

　　9、origins-originate 词性混淆。Origin是名词意思是“起源，由来”，动词形式为originate意思是“引起，起源”

　　10、comparative-comparable词汇错误。句意为：谷地网络考试吧呈现变种度量特征，包括与陆地流域盆地相似的网状密度。应用可比较的comparable。