题型：问答题 简答题 已知三条不同的直线a，b，c在同一平面内，下列四个命题：①如果a//b，a⊥c，那么 b⊥c； ②如果b//a，c∥a，那么 b// c； ③如果 b⊥a，c⊥a，那么 b⊥c； ④如果 b⊥a，c⊥a，那么 b//c. 其中真命题的是（ ）（填写所有真命题的序号) 查看答案
题型：问答题 简答题 完形填空。 Hong Kong has about forty public beaches.1_____ of the beaches are the best in the 2_____. People can 3_____ swimming there. You can go to most of them by 4_____. To get to some beaches,you must take a boat. There are toilets, changing rooms and places to 5_____ food and drink on most of the beaches. You can swim there 6_____ any danger if you remember these instructions (说明): 1. Never swim by yourself (独自). 2. Never swim after a meal or when you feel 7_____or tired. 3. 8_____ stay in the water too long. 4. Never go out in a boat without a life jacket if you can't swim. Remember: A red flag (旗) means that it is 9_____ for anybody to go into the water. A blue flag means that it is only dangerous for 10_____.( )1. A. All ( )2. A. town ( )3. A. go ( )4. A foot ( )5. A. sell ( )6. A. with ( )7. A. happy ( )8. A. Don't ( )9. A. good ( )10. A. people B. One B. world B. do B. plane B. buy B. before B. sad B. Can't B. dangerous B. teachers C. Some C. place C. have C. bus C. keep C. without C. busy C. Mustn't C. bad C. children D. No D. village D. see D. horse D. eat D. after D. h ungry D. Didn't D. safe D. students 查看答案
题型：问答题 简答题 随着收入的提高，我市拥有私家车的家庭越来越多了，汽车尾气对空气污染很大，下列不能很好解决这个问题的方案是[ ]A．用无铅汽油，且过滤尾气B．扩大绿化面积C．有计划地控制汽车流量D．拓宽交通路面 查看答案