＃长难句每日一句＃是一道配菜，建议你首先消化课程所讲内容之后，再每天来一个长难句来填满碎片时间。切不可不听，每天只练一个长难句，那就本末倒置了。
长难句的正确打开方式：先尝试自己分析，然后看下面的解析如何任何问题（学习情感职场）可以直接分解提问
One basic weakness in a conservation system based wholly on economic motives is that most members of the land community have no economic value.在一个完全以经济目标为基础的(生态)保护系统中，一个根本弱点在于陆地群落的大多数成员没有经济价值。Yet these creatures are members of the biotic community and, if its stability depends on its integrity, they are entitled to continuance. When one of these noneconomic categories is threatened and, if we happen to love it .We invert excuses to give it economic importance.【结构分析】
首句是由and连接的并列句，前半句为主系表结构，即：these creatures /are/ members of the biotic community.
and之后的后半句由if引导条件状语从句和主句构成。
“and”连接“when” 引导时间状语从句与“if”引导的条件状语从句，句子主干为主谓宾结构，即：we/invented/ excuses…; “to give it economic importance” 为目的状语。
noneconomic /'nɔn,i:kə'nɔmik/ adj. 无实用价值的；无经济价值的category /ˈkætəɡəri/ n. (人或事物的)类别,种类threaten / ˈθretn / vt. 扬言要；威胁；恐吓invent / inˈvent / vt.编造；揑造；虚构excuse / ikˈskju:s / n. 藉口；理由creature / ˈkri:tʃə(r) / n. 生物；动物biotic / baiˈɔtik/ adj. 生物的；生命的stability / stəˈbiləti / n. 稳定(性)；稳固(性)integrity / inˈteɡrəti / n. 完整；完好continuance / kənˈtinjuəns / n. 继续Yet these creatures are members of the biotic community and, if its stability depends on its integrity, they are entitled to continuance. When one of these noneconomic categories is threatened and, if we happen to love it, we invented excuses to give it economic importance.但是这些生物是生物群落的成员，并且如果该群落的稳定性依赖其完整性，那么这些生物有权/应该继续生存。当这些无经济价值的物种之一受到威胁时，并且如果我们正好喜欢它，我们就会编造理由来赋予其经济价值。At the beginning of century songbirds were supposed to be disappearing. Scientists jumped to the rescue with some distinctly shaky evidence to the effect that insects would eat us up if birds failed to control them.
