Nora is an American girl. She studies in a middle school. She has a little sister. Her name is Kate. Kate is only four. Nora likes Kate very much. 
Today is Sunday. Nora wants her pen. She takes out her pencil box. “ Oh , dear! Where’s my pen?” She can’t find her pen. She goes to ask her sister in her bedroom.
“Kate! I can’t find my pen. Can you see……Oh, what are you doing with (用) my pen?”
“I’m writing to my friend, Betty.” Kate answers. “But how can you? You don’t know what to write.”
“It doesn’t matter (没关系). Betty can’t read.” Kate says.

 2015年3月9日，全球最大太阳能飞机“阳光动力2号”，在阿联酋首都阿布扎比发射，开始5个月的环球飞行．机翼安有1.7万块太阳能电池板，翼展72米，重量仅相当于一辆汽车．太阳能电池板是将太阳能转化为 ____能，在空中飞行时是根据 ____原理获得升力的．飞行员通过 ____和地面指挥中心相联系