Mrs. Thompson came to the 5th grade class and noticed that Teddy was always alone. Also, he did badly in his studies. When she reviewed Teddy’s past records，she find he was a good child at first，but he began to change when his mother got ill. Finally he lost interest in school after his mother’s death.
   Mrs.Thompson realized the problem and felt sorry for him. She felt even worse when her students brought her beautifully-covered Christmas presents. His presents were covered with some old paper. Some children laughed when she found a bracelet(手镯)with some of the stones missing, and a bottle with a little perfume(香水). But she said how pretty the bracelet was, putting it on, and dabbing some perfume on her hand. Teddy stayed after school for a long time just to say，“Mrs.Thompson，today you smelled just like my mom used to.” After the child left，she cried for quite a long time.
   On that very day，she taught not only knowledge but also children. As she worked with Teddy，his mind seemed to come alive. By the end of the year，Teddy had become one of the smartest children in the class.
   A year later，Teddy left school. She found a note under her door，from Teddy，saying that she was the best teacher he ever had in his life. After that, these words were repeated in each of his letters to her.
   Then after he finished college, Teddy wrote telling her that he had met a pretty girl and was going to get married. He explained that his father was dead，and that he wondered if Mrs.Thompson might sit at the wedding in the place for the mother of the groom(新郎).
Of course，Mrs.Thompson did. She wore the bracelet and the perfume that Teddy remembered his mother wearing on their last Christmas together.
   They hugged(拥抱)each other，and Teddy whispered in Mrs.Thompson's ear，“Thank you，Mrs.Thompson，for making me feel important，and showing me that I could make a difference. ”
   Mrs.Thompson，with tears in her eyes，whispered back，“Teddy，it's not like that. You were the one who taught me that I could make a difference. I didn’t know how to teach until I met you.”

二甲醚（CH₃OCH₃）可由一氧化碳和物质X在一定的条件下制得。反应的化学方程式为，则X的化学式为

下列各句中，没有语病的一项是（     ）

阅读下文，回答相关问题。

      【甲】水陆草木之花，可爱者甚蕃。晋陶渊明独爱菊；自李唐来，世人皆爱牡丹；予独爱莲之出淤泥而不染，濯清涟而不妖，中通外直，不蔓不枝，香远益清，亭亭净植，可远观而不可亵玩焉。
       花之隐逸者也；牡丹，花之富贵者也；莲，花之君子者也。噫！菊之爱，陶后鲜有闻；莲之爱，同予者何人？牡丹之爱，宜乎众矣！
                                                                                                                                               ——选自周敦颐《爱莲说》
      【乙】竹似贤，何哉？竹本^（1）固，固以树德，君子见其本，则思善建不拔者。竹性直，直以立身；君子见其性，则思中立不倚者。竹心空，空似体^（2）道；君子见其心，则思应用虚受^（3）者。竹节贞，贞以立志；君子见其节，则思砥砺名行、夷险一致者。夫如是，故君子人多树之为庭实^（4）焉。
                                                                                                                                              ——节选自白居易《养竹记》
      【注释】（1）本：根。（2）体：体悟。（3）虚受：虚心接受。（4）实：充实，充满。