67. The main problem of Yosemite National Park is its _______. (A) rundown water pipes (B) overcrowdedness (C) lack of money (D) narrow roads

66. National parks like Yosemite in the U.S. find it increasingly difficult to meet the need of visitors because ________. (A) their transport management needs improving (B) they spend too much on their service systems (C) their service systems frequently go out of order (D) they need help from environmental organizations