【正确答案】：
(1)MANY IDIOMS WERE CREATED IN DIFFERENT PROFESSIONS, SO THEY WERE TRADE-OR PROFESSION-RELATED, COLLOQUIAL AND INFORMAL.
(2)NOW MOST BECOME A PART OF THE COMMON CORE, NEITHER FORMAL NOR INFORMAL.
(3)THERE ARE STILL MANY COLLOQUIALISMS, SLANG EXPRESSIONS, LITERARY EXPRESSIONS COMPARATIVELY SMALL IN NUMBER.
【题目解析】：（1）许多成语是在不同的职业中产生的，因此它们是与行业或职业相关的、口语化的和非正式的。（2）现在大多数习语都成为共同核心的一部分，既不是正式的也不是非正式的。（3）口语、俚语、文学表达数量相对较少。