The second largest stock exchange in the U.S. used to be called .

• A、the Wall Street Exchange

• B、the New York Stock Exchange

• C、the Curb Exchange

• D、the U.S. Exchange

57（）

The article does not say whether the scientists’ experiments with dogs have .

• A、benefited animals other than dogs

• B、served man

• C、helped other dogs

• D、contributed to medical knowledge