题目

选择可以替换句中画线部分的最佳答案。 (  )1. Look out ! A car is coming. A Look carefully  B. Have careful  C. Be careful  D. Look up (  )2. We will have to plant twenty more trees. A. more than twenty    B. another twenty C. the other twenty     D. less than twenty (  )3.They had a good time at the park last Sunday. A. good luck    B. enjoyed themselves    C. had a good weekend    D. had a rest (  ) 4. Grandma is ill . Let’s take her to the hospital right away . A. at first     B. on time     C. from now on    D. at once (  )5.已知直角梯形ABCD的下底与等腰直角三角形ABE的斜边重合，AB⊥BC，且AB=2CD=2BC（如图1），将此图形沿AB折叠，使得平面ABE⊥平面ABCD，连接EC、ED，得到四棱锥E﹣ABCD（如图2）．（1）求证：在四棱锥E﹣ABCD中，AB⊥DE．（2）设BC=1，求点C到平面EBD的距离．