Mabel was a naughty boy and he was not good at his study. “Could do better” were usually the 1 at the bottom of his report card. His parents 2 Mabel's marks a lot. How they wished Mabel made a little progress. But whenever they got his report card, they were quite disappointed, 3 their heads.

     At the end of the term, the report card would be sent home. Mabel wished to find a safe place away from the 4 faces of his parents. One morning, when Mabel was still in bed, his mother rushed into his room, holding the report card in hand. “Well done, son. You are number one in the class. You are our 5.” She gave Mabel a big kiss. Mabel could not believe it, 6 he looked at the report card carefully.

     Very soon, Mabel found out it was Manuel's report card, not his. The teacher had made a 7. His mother had left, busying calling all the family about the 8 news. Mabel wondered what the right thing to do was. He thought for a while, whether to please his parents 9 to be an honest boy. Finally, he decided to tell his parents the 10.

在四边形ABCD中，若$\overrightarrow{AB}+\overrightarrow{AD}=\overrightarrow{AC}$，且$\left(\overrightarrow{AB}+\overrightarrow{AD}\right)·\left(\overrightarrow{CB}-\overrightarrow{CD}\right)=0$，则（ ）

我国第二级和第三级阶梯的分界线是（　　）

阅读古诗，回答问题

卜算子•咏梅

陆游

   驿外断桥^①边，寂寞开无主^②，已是黄昏独自愁，更著^③风和雨。

无意苦争春，一任^④群芳妒，零落^⑤成泥碾作尘，只有香如故。

      【注释】①断桥残破的桥。②无主无人过问。③更著又遭受。著，同“着”，遭受的意思。④一任任凭。⑤零落凋谢。