Etymology, the study of words and word roots, may sound like the kind of thing done by boring librarians in small, dusty rooms．Yet etymologists actually have a uniquely interesting job．They are in many ways just like archaeologists (考古学家) digging up the physical history of people and events．The special aspect of etymology is that it digs up history, so to speak, through the words and phrases that are left behind．
The English language, in particular, is a great field to explore history through words. As a language, English has an extraordinary number of words．This is partly due to its ability to adapt foreign words so readily．For example, "English" words such as kindergarten (from German), croissant (from French), and cheetah (from Hindi) have become part of the language with little or no change from their original sounds and spellings. So English-language etymologists have a vast world of words to explore．
Another enjoyable thing about etymology for most word experts is solving word mysteries(谜)．No, etymologists do not go around solving murders, like the great detective Sherlock Holmes．What these word experts solve are mysterious origins of some of our most common words
One of the biggest questions English language experts have pursued is how English came to have the phrase OK．Though it is one of the most commonly used expressions, its exact beginning is a puzzle even to this day．Even its spelling is not entirely consistent-unless you spell it Okay, it is hard even to call it a word．
Etymologists have been able to narrow OK’s origin down to a likely, although not certain, source(来源)．It became widely used around the time of Martin Van Buren's run for president in 1840. His nickname was Old Kinderhook. What troubles word experts about this explanation is that the phrase appeared in some newspapers before Van Buren became well known．It is likely that Van Buren could be called its primary source Etymologists will doubtlessly keep searching for the initial source．However, it is clear that OK’s popularity and reputation have topped those of the American president to whom it has been most clearly linked．
The author mentions the words like "croissant" in Paragraph 2 to indicate________．

A．words have changed a lot in the two languages

B．what English-language etymologists are exploring now

C．English has absorbed many words from other foreign languages

D．the English vocabulary is difficult to the non-English-speaking people

The underlined word "pursued" in Paragraph 4 means___________．

A．looked upon

B．dug up

C．put in

D．set down

We can learn from the passage that etymologists_______．

A．discover the possible origin of words

B．help detectives to solve mysterious murders

C．write interesting stories for some newspapers

D．explore the English language as well as the recent events

What is the main purpose of the passage?

A．To present the history of English words.

B．To explain the procedure of an etymologist's job.

C．To introduce the pleasure of the study of words and word roots．

D．To teach readers how to distinguish English and non-English words