How "policeman", "constable", "bobby" and "cop" differ in the se

How "policeman", "constable", "bobby" and "cop" differ in the sense of connotation?
【正确答案】：

AMONG THEM, "POLICEMAN" AND "CONSTABLE" ARE STYLISTICALLY NEUTRAL, YET THE FORMER IS USED BOTH IN BRITISH ENGLISH AND AMERICAN ENGLISH WHILE THE LATTER IS ONLY IN BRITISH. "BOBBY" IS COLLOQUIAL, USED ONLY IN BRITISH ENGLISH AND "COP" IS SLANGY.

【题目解析】：Among them, "policeman" and "constable" are stylistically neutral, yet the former is used both in British English and American English while the latter is only in British. "Bobby" is colloquial, used only in British English and "cop" is slangy. 其中，policeman和constable在文体上是中立的，而前者在英式英语和美式英语中都有使用，而后者仅在英国使用。bobby口语化，只在英式英语中使用，cop是俚语。