Questions 14 to 17 are based on the following passage. At the end of the passage, you will be given 20 seconds to answer the questions.
Plenty of day hikes go to the following places EXCEPT ______.

A．Information on all works is accessible on cell phone provided by the museum.
B．Radio tours have been part of the National Gallery since the 1960s.
C．The digital technology gives visitors more freedom.
D．The visitors can borrow an mp3 player at no cost.

A．Heating the water.
B．Letting the water flow out.
C．Letting water flow into the system.
D．Holding water for the system.