1.首先判断so和and，根据句意前后关系应该是因果而非并列，所以排除and选项D,E
2. so as to主语和主句主语一致所以排除A
3. wasted water和water wasted明显应该是water wasted in there因为wasted water不知道是谁把水waste了

The phrase “so as to” means “in order to.” Now, the sentence says that land graders can flatten uneven farmlands “so as not to” = in order not to waste rainwater. So, the sentence suggests that the previous models of land graders used to waste rainwater. But this advanced model can flatten uneven land not to waste water. This meaning is illogical because land graders do not waste water any which way. Land graders have got nothing to do with rainwaters. This sentence presents an illogical meaning and hence is incorrect.

C. 不是there is no wasted rainwater 而是 there is no rainwater wasted

A：看起来像graders浪费了rainwater
C：there is no rainwater wasted
E：前后是有目的关系，并非并列。

so as to 的主语是句子的主语，压土机本身不会浪费水
waste water is done by the whole action

so as to=so that，但是需要注意前者需要保持主语一致，后者不需要

考点：动词的过去分词作被动态vs. adj.。
The phrase "there is no wasted rainwater" isn't necessary when the passive form "rainwater is not wasted" is shorter and even clearer to readers.

这里there is no wasted rainwater进行了限定，没有wasted rainwater，但是有没被浪费的rainwater??? 明显与almost perfectly不符合。如果改成there is no rainwater wasted，其实是对滴，当然有wordy的嫌疑，不是核心错误。

借鉴：https://gmatclub.com/forum/evidence-of-some-shifts-in-the-character-of-violence-on-television-is-296906.html。

graders can flatten farmland so as not to waste rainwater -- graders waste rainwater--- doesn't make sense

As in choice A, this choice suggests that the graders themselves might waste rainwater.

D. 并不在于接两个完整句子，and 后面有thereby，所以可以是一个subject， 但是因此就有问题，引用官方解析如下：
“As in choice A, this choice suggests that the graders themselves might waste rainwater.”

so as to 主语 grader 本身不会浪费水

非划线IN 前面 wasted in runoff 也很顺

there is多余累赘，so as to的主语是grader，并不是通过做了什么才不浪费水。而是他把地整平了，继而不会滑坡漏水。排除14

By peggy卓 ：Graders do not save or waste. They are just machines.

sc
A. so as to 的主语是句子的主语，压土机本身不会浪费水
C. 不是there is no wasted rainwater 而是 there is no rainwater wasted
D. and应连接两个句子
E. 根据句子逻辑应该是前面导致后面的发生，故应用so that 连接较好

so as to的主语

A. so as to 的主语是句子的主语，压土机本身不会浪费水
C. 不是there is no wasted rainwater 而是 there is no rainwater wasted
D. and应连接两个句子
E. 根据句子逻辑应该是前面导致后面的发生，故应用so that 连接较好

Graders do not save or waste. They are just machines.
there is . . . form is wordy