Sophisticated laser-guided land graders can now flatten uneven farmland almost perfectly so as not to waste rainwater in runoff down sloping fields.
考点： so as to ,so that当前版本由 Emma冲7鸭 更新于2019-12-01 03:12:38 感谢由 Emma冲7鸭 对此题目的解答所做出的贡献。
A.so as not to主语要一致，不是主语graders waste rainwater
D 同样，主语grader 不能waste
Logical predication; Rhetorical construction
The sentence is meant to indicate that the purpose of flattening uneven farmland is to prevent the waste of rainwater in runoff.
Note that purpose can be expressed in various ways, including by the use of a clause beginning with so that.
A. In this choice, the implicit subject of the verb waste is the graders. That is, it suggests that these machines would themselves waste water unless they flattened land.
B. Correct. This choice avoids errors found in the other choices and contains no other errors.
C. This choice is incorrect because it unnecessarily uses the wordy there is . . . form; it would be more concise to use the passive-voice verb form no rainwater is wasted, as in choice B.
D. As in choice A, this choice suggests that the graders themselves might waste rainwater.
E. This choice omits the element of purpose conveyed by so that in choice B: and fails to convey purpose. As in choice C, the wordy form there is . . . is used.
The correct answer is B.
逻辑：先进的激光制导土地平整机现在可以将不平整的农田几乎完美地压平，这样做的目的是 雨水就不会在坡地的径流中浪费掉。 A，so as to的主语是一致的，so that主语可以不一致；后面的主语是graders，graders不会浪费雨水，而应该是这件事的目的是不会浪费雨水（better）。 C，there be wordy；被动语态都优于there be； D，and后面省略的主语是land graders，同A一样错。 E，①没有so that这层表目的的意思；②there be