Part IV Cloze (15 minutes)
A language is a signaling system 这里对语言下个一个定义,类似的句型还有 A language refers to / is defined as which operates with symbolic vocal sounds (语声), and which is used by a group of people for the purpose of communication.
Lets look at this 61 in more detail because it is language, more than anything else, 62 distinguishes man from the rest of the 63 world. 61题this definition指代第一句话的内容; it is language that是强调句. 下面一段第一句other animals 暗示了63题填animal

distinguish from 表示对比概念. 大家都知道,对比型文章在阅读,完形和改错中都经常出现,所以必须首先掌握这类文章的一些词汇特征,解题的时候也要注意对比概念. 表示对比概念的词汇手段很多,举几个例子 distinct from / differ from / different from / similar to / dissimilar from / in contrast to / on the contrary / as opposed to / while / whereas / but / however 等等
Other animals, it is true, communicate with one another by 64 of cries 本句也可以变为It is true that other animals communicate with….., 那为什么要写成本文这样呢.如果能知道，大家对英文的理解为更深刻. 这里以other animals 为主语, 使本句话与上一段最后一句衔接更紧密, 因为animals是 上句中出现过的概念. 举个作文的例子,很多同学写作文的时候句子之间缺乏coherence, 比如 He got off the plane. Reporters surrounded him. 这两句话虽然没错,但是最好改为He got off the plane. He was surrounded by reporters 或He got