单项选择题
A. To select top students. B. To know who had received ordinary schooling. C. To put students in a right order. D. To make sure who required particular treatment.
A. They tell us which one of the tracks the universe will use. B. They enable us to alter the course of universe. C. They give us information about the lunar surface. D. They determine which course the universe will take in the future.
A. part of a historical cave system B. the biggest underground lake in the world C. listed in the Guinness Book of World Records D. the largest body of water in Tennessee