GRE考试

根据网考网考试中心的统计分析，以下试题在2019/8/13日GRE考试习题练习中，答错率较高，为：69%
【单选题】It can be inferred from the passage that scientists are "perplexed by the means" (line 12) for which of the following reasons
A、They are unsure of how alanine remains separate from the everyday nitrogen metabolism of the plant itself.
B、They have yet to establish what function the alanine serves for the soybean plants.
C、They have thought alanine to exist only in very small quanties in rhizobiA、
D、They have long considered the membranes of the soybean plant impermeable to amino acids.
E、They are uncertain how such a rapid export of fixed nitrogen is possible through the soybean membranes.
网考网参考答案：D，答错率：69%
网考网试题解析：
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