4.Touch: the chocolate should melt easily in your mouth becoming a thick liquid.

　　5.Taste: good chocolate should not taste too sweet or too bitter.

3. Why does the author mention opioids in Paragraph 2?

A. To prove chocolate contains the same chemicals as opioids.

B. To show the sharp contrast between chocolate and opioids.

C. To suggest that chocolate is as highly addictive as opioids.

D. To help explain the reason why chocolate brings pleasure.

4. The underlined word "it" in Paragraph 3 refers to _______.

A. anandamide B. chocolate C. opiate D. Brain

5. Which of the following best suits "perfect chocolate" according to chocolate makers?

A. Milk chocolate that produces a dull sound when broken.

B. Milk chocolate that has shiny appearance and bitter taste.

C. Dark chocolate that is easy to melt and of moderate taste.

D. Dark chocolate that gives off a sweet and deep fragrance.

　　C

　　Bottle Cap Alley is a unique roadside attraction located at the north edge of the Texas A&M University campus, in College Station Texas. As the name suggests, it is paved with hundreds of thousands - by some accounts, millions - of beer and soda bottle caps.

　　No one knows exactly how the tradition of paving the 50-meter-long by

2-meters-across alley with metal caps began, but seeing as it is located between the iconic Dry Bean pub and the Dixie Chicken restaurant, some people believe that it started out as a dumping site for the two establishments. Patrons who took their drinks outside followed their example, and as word of the Bottle Cap Alley spread, other local bars started bringing in their nightly haul of bottle caps here as well. It is estimated that the tradition goes back four decades.

Bottle Cap Alley was officially recognized as a local attraction in the early 2000s, when local authorities recognized its potential as a place of interest for tourists. They set up a large sign over it, added lights so it could be visited at night and began promoting it as a part of the local sightseeing tour. The move didn't sit well with many college students, who wanted to make the tradition survive forever, but it did turn the once obscure alley into a popular roadside tourist