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it left behind it a trail of, 它身后留下一串……。
a trail of作left的宾语，behind it是状语，提到宾语之前是为了使句子结构更紧凑。
puma fur was found clinging to bushes中，clinging是现在分词，此处作主语puma fur的主语补足语。下文中As no pumas had been reported missing…一句中，missing也是现在分词作主语补足语。
Complain of /about sth 抱怨，控诉
Complain that …
He began to complain about the weather.
Some children complain that their parents nag at them.
on + 名词：强调动作正在进行
on the rise:在上升
on the increase: 在增加
on the watch: 在观看
on the match:在比赛中
on the fishing trip:在钓鱼的途中
★convince
v. 使……信服
convince sb.of sth.
和宾语从句that搭配使用
没有宾语的情况下要采用主系表结构：be convinced
