Jack Black has a big 1. His grandfather and grandmother 2in England. They are at home. Their 3 are Nick Black and Anna Black. But Jack’s parents are in China. Jack’s 4 is an English teacher. He works in a middle school. Jack’s mother 5 a teacher. She is a doctor (医生). Jack and his 6 Mary are students. They go to the same (同一个) 7 in Beijing. Jack is 8 Class One, Grade Seven. At school Jack has 9 good friends. They are Lin Feng, Li Lei, and Sun Weiming. Mary has many good friends, too. They 10 their school.

词语搭配

无边的____    小诗

白色的____    带子

奇丽的____    大花

迂回的____    绿毯

如图所示，A、B为两块足够大的相距为d的平行金属板，接在电压为U的电源上．在A板的中央P点放置一个电子发射源．可以向各个方向释放电子．设电子的质量为m、电荷量为e，射出的初速度为v．求电子打在B板上的区域面积？(不计电子的重力)

 淮安市某盐化厂生产的碳酸钠粗产品中含有少量氯化钠．碳酸钠和氯化钠的溶解度与温度的关系如图所示，回答下列问题：

（1）t₁℃时碳酸钠与氯化钠中溶解度较大的物质是____ ．

（2）t₁℃时碳酸钠溶液升温至t₂℃，所得溶液的溶质质量分数____ ．（填“变大”、“变小”或“不变”）．

（3）除去碳酸钠中混有少量氯化钠的方法是____ ．

函数$y=\sqrt{-x^2+9}$的值域为（   ）