Lesson 1 A Puma at large
（1）Pumas are large,cat-like animals which are found in America.
主系表结构，句子主干是Pumas are animals。which定语从句修饰animals
（2）When reports came into London Zoo that a wild puma had been spotted forty-five miles south of London, they were not taken seriously.
被动语态。when引导的状语从句表示时间，that引导reports的同位语从句，they作为代词指代reports。正常语序应是People didn’t take those reports seriously.
（3）However, as the evidence began to accumulate, experts from the Zoo felt obliged to investigate, for the descriptions given by people who claimed to have seen the puma were extraordinarily similar.
主系表结构。主干是experts felt obliged。典型的however用法，表示转折。as引导时间状语从句，表示同时发生。to investigate做表语的补足语，for引导原因状语从句，从句主干是the descriptions were similar，given by是过去分词短语作定语，修饰descriptions，who引导的定语从句修饰限定people。
（4）The hunt for the puma began in a small village where a woman picking blackberries saw 'a large cat' only five yards away from her.
主谓结构，主干是Thehunt began。for表示目标，in a small village 是介词短语表地点，where引导的状语从句表示地点，先行词是village，picking blackberries是现在分词短语作定语修饰限定woman。
（5）It immediately ran away when she saw it, and experts confirmed thata puma will not attack a human being unless it is cornered.
and引导的两个并列句。第一个句子是主谓结构，主干是Itran. away做补语，when引导的状语从句表示时间。第二个句子在主干是主谓宾结构，experts confirmed that宾语从句。unless引导条件状语从句。
（6）The search proved difficult, for the puma was often observed at oneplace in the morning and at another place twenty miles away in the evening.
主系表结构，Thesearch + proved +difficult，for引导的状语从句表示原因，从句是被动语态。
（7）Wherever it went, it left behind it a trail of dead deer and smallanimals like rabbits.
主谓宾结构，it+ left + a trail of dead deer and small animals like rabbits. wherever引导地点状语从句。
（8）Paw prints were seen in a number of places and puma fur was foundclinging to bushes.
and引导的两个并列句。两个句子都是被动语态，强调动作，而执行动作的主语则非特定或不重要。第二个句子是主谓宾宾补结构，正常语序下应为People+ found + puma fur +clinging to bushes，现在分词短语作宾语补足语。
（9）Several people complained of "cat-like noises' at night and a businessman on a fishing trip saw the puma up a tree.
and引导并列句。
（10）The experts were now fully convinced that the animal was a puma, butwhere had it come from?
（11）As no pumas had been reported missing from any zoo in the country,this one must have been in the possession of a private collector and somehowmanaged to escape.
主系表结构+主谓结构。主干是this one + must have been + 介词短语作表语and+谓语动词。
（12）The hunt went on for several weeks, but the puma was not caught.
but引导两个并列句子。第一个句子是主谓结构，thehunt + went on。第二个句子是被动语态。
（13）It is disturbing to think that a dangerous wild animal is still at large in the quiet countryside.
主系表结构，It+ is + disturbing。it做形式主语，不定式短语tothink that从句是真正的主语。
