the policeman finds a boy（ ）【原型是look】out of the window of the bus 附带讲解
问题描述：
the policeman finds a boy（ ）【原型是look】out of the window of the bus
附带讲解
答
looking，发现他正在往窗外看
答
填looking。这里looking（现在分词）做句子的补语，表示进行。整个句子the policeman finds a boy looking out of the window of the bus =the policeman finds (that) a boy is looking out of the window of the bus 。不过不同的是前面那个句子是一个简单句，后面那个句子是一个宾语从句。
答
the policeman finds a boy（looking ）【原型是look】out of the window of the bus
答
looking
警察发现时 一定是男孩的动作正在进行
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