OG 阅读第69题

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答案是 A，可我根据最后一句的定位却怎么也不懂怎么答案会是A呢，望高手指教！

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後一句再回應文章中的重點oligosaccharin 是specific

以此concept 來做答

(A) To stimulate a particular plant cell to become part of a plant’s root system (oligosaccharin是specific ß> particular )

(B) To stimulate the walls of a particular cell to produce other oligosaccharins（oligosaccharin 是由enzymes release 的詳見L37）

(C) To activate enzymes that release specific chemical messengers from plant cell walls（詳見L36--37）

(D) To duplicate the gene complement in a particular plant cell（有嗎?）

(E) To produce multiple effects on a particular subsystem of plant cells（oligosaccharin是specific）