Every weekend is important to the Franklin's family. During the week they don't have very much time together, but they spend a lot of time together on the weekend.

    Mr. Frankin works at the shoe store downtown during the week, but he doesn't work there on the weekend. Mrs. Franklin works at the city hospital during the week, but she doesn't work there on the weekend.

    Bobby and Sally Franklin go to the junior high school during the week, but they don't go there on the weekend.

    And the Franklin's dog Rover stays at home alone during the week, but he doesn't stay at home alone on the weekend.

下列地形中有“世界屋脊”之称的是（     ）