51＿＿

17.The teacher asked all the students in the class to keep their eyes＿for a minute.

• A、close
• B、closed
• C、to close
• D、closing

39.The word"underdog”in Paragraph 1 probably refers to(  )

• A、smart high school students
• B、dogs that are not liked by their owners
• C、students who need help to succeed
• D、poor company workers