2018年高考英语二轮复习组合练16：阅读理解＋书面表达
【语篇解读】 本文是一篇说明文。文章主要介绍了植物受到袭击时会释放出某种化学物质来保护自己并“告知”附近的植物。
5．What does a plant do when it is under attack?
A．It makes noises.
B．It gets help from other plants.
C．It stands quietly.
D．It sends out certain chemicals.
解析：细节理解题。根据第一段中的“...reported that young maple trees getting bitten by insects send out a particular smell that neighboring plants can get.These chemicals come from the injured parts of the plant and seem to be an alarm.”可知，植物受到伤害时会散发出一种特殊的气味，而这种特殊的气味就是某些化学物质，故选D项。
A、B两项无中生有，文章并没有提及制造声响和从其他植物那儿获取帮助的信息；C项曲解文意，第一段中的“...it doesn\'t sit quietly.”不等于“It stands quietly.”。
答案：D