【正确答案】：
（1）AN IDIOM MAY CONSIST OF MORE THAN ONE WORD, EACH HAS ITS MEANING, AND PART OF SPEECH.
（2）HAS A SINGLE MEANING.
（3）FUNCTIONS AS ONE WORD-EQUIVALENT.
（4）IN MANY CASES, ILLOGICAL RELATIONSHIP BETWEEN THE LITERAL MEANING OF THE CONSTITUENT WORD AND THE MEANING OF THE WHOLE IDIOM.
【题目解析】：（1）习语可以由一个以上的词组成，每个词都有自己的含义，是言语的一部分。（2）具有单一含义。（3）相当于一个词的功能。（4）在许多情况下，构成词的字面意思与整个习语的意思之间是不合理的关系。