根据短文括号内所给汉语意思，在空白处写出单词的正确形式。每空一词

 Last ____ (圣诞节) Day, when I was at the street ____ （角落）, a car ____ （经过） by. The car stopped in front of me. A woman looked out of the car and asked me  ____ （有礼貌地）, “Excuse me, could you tell me the right direction to the  station?” Oh, my god! She was my old classmate. She used to be a shy girl. She didn’t ____（敢于）to speak in ____ （公众）. But her English was good and she did well in the ____ （发音） and the ____ （语法）. I____ （羡慕） her very much. Finally we had a happy  ____ （谈话） and I told her the way to the station.

关于二次函数$y=-\frac{1}{3}{\left(x-5\right)}^2+3$的图象与性质，下列结论错误的是（  ）

如图表示了初中化学中一些常见物质的相互转化关系(部分反应条件已省略)。下列说法错误的是（）

如图，半径为2的⊙O中，∠AOB=90°，D为OB的中点，AD的延长线交⊙O于点E，则线段DE的长为____