“在美国宣称阿波罗计划成功的约半个世纪之后，我们也将自己的登月计划提到了议事日程，事实已经证明，我们有能力征服太空，有能力将中国人从地球引力的束缚中暂时的解脱出来，去探寻那未知的宇宙奥秘。”最能证明我们“能力”的事件是（   ）

   In many high schools，there are strict rules about using mobile phones. If your phone rings in class，for example，the teacher will be very angry.
   Every mobile phone has a ringtone (铃声). It tells you that someone is calling you. Now，there is a ringtone called “mosquitotone (蚊子铃声)”. Using it，students can receive calls and text messages (短信) in class but the teacher will not realize what is happening. How?
   Mosquitotone has a special sound. Only children and teenagers can hear it. As we get older，we are unable to hear some sounds with high frequencies (频率). As a result，a child or teenager can hear the mosquitotone ringtone, but it's_inaudible_to someone 20 or older.
   But sometimes，people over 20 can hear the ringtone. One British student's phone uses mosquitotone. In class，the student's phone rang. The 32­year­old teacher looked at the student and became unhappy. “I heard that. You know the rule：no mobile phone in class.”
   Not all the students are interested in mosquitotone. Jerry Jones，a high school student of 17，says，“Using mosquitotone too often is bad for our hearing. I may use it for pleasure，but not in class. It's unfair to the teachers！”
   What do parents think of mosquitotone？“I think it is perfect for places like movie theaters，” says Connie Neeson,44.“Think about it. Yon're watching a film and someone's mobile phone rings. Mosquitotone is good because many people don't hear it. However，it also has a bad influence on their study if students use it in class.”

下列不属于世界人口稠密区的是（　　）

下列哪一城市既是近代第一批被迫开放的通商口岸，又是现代第一批主动开放的经济特区（   ）

如图，在平面直角坐标系中，以O（0，0），A（1，1），B（3，0）为顶点，构造平行四边形，下列各点中不能作为平行四边形顶点坐标的是（    ）