题目

完形填空。 Marta's family moved to a new town.Marta was _1__worried than excited about her first day at her new school.She was worried that her __2__ classmates would not talk to her.How could she make new friends at the new school？She was not sure.When Marta walked into the classroom，the first__3__ she saw smiled (微笑)at her.She seemed __4__．Marta felt happy and smiled back and said hello to the girl.However，the girl didn't __5__．She just put her hand in Marta's and waved it back and forth (来回地摇动)． Marta was a little surprised.__6_ didn't the girl say hel同学们在“探究小灯泡的亮度与功率的关系”实验中，所用电源电压为6V，灯泡的额定电压U0=3.8V，额定功率在1﹣1.5W的范围内．（1）按图甲所示的电路图，请你用笔画线代替导线将图乙的电路补充完整． （2）小杜同学在实验过程中，将滑动变阻器的滑片P缓慢向B端移动，小灯泡的实际功率将（选填“变大”、“变小”或“不变”）；同时观察到小灯泡的亮度将变（选填“亮”或“暗”）．（3）另一组的小张同学在实验过程中发现电流表、电压表示数如图丙所示，此时电流表的示数是A，电压表的示数是V，经分析造成这种现象的原因是 ． （4）小张同学重新调整电路连接后，继续探究小灯泡在额定功率时的亮度，但发现无法准确读出额定电压，他用第（3）小问中所测得数据先算出灯泡的电阻RL ， 再根据P0= 计算灯泡的额定功率．按此方案算出灯的额定功率比真实值偏（选填“大”或“小”），原因是 ．