在不断增长的癌组织中，每个癌细胞(　　)

在△ABC中，DE∥BC，DE将△ABC分成面积相等的两部分，那么DE：BC=（　　）

阅读下面短文，从短文后所给各题的四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项。

    My first lesson is at a meeting. As we settle around the table I hear Meg, who is 1 a recent operation, talking to Judith, the manager of our project. “Thank you so much for 2 my daughters to their dance lessons last week.” “Don't mention it,” Judith says, “It was nothing.”

    Knowing how 3 Judith's schedule is, with her work, kids and aging parents, I find her driving Meg's children to lessons unbelievably 4. I am about to say more about this when Donna, another colleague, enters the room 5. She apologizes for being late, saying she just hosted a lunch for her friends who are over seventy. “That is so nice of you,” I say, 6 how busy she is, how she doesn't like to cook and clean. “Oh,” she says, waving her hand, “It was nothing.” 7, I can still tell the 8 in her voice. She did gain a sense of satisfaction from the entertainment offered to her friends.

    Seeing their 9 to help others selflessly, I start thinking about the concept of “nothing”, this peaceful and generous way of living — had it really been nothing or are they simply saying that? It 10 to me that once I spent a whole afternoon after work helping a friend 11 a speech she was going to deliver. I 12 her to rearrange the sequence of the stories in the lecture to make it sound more 13. After the fifth try, she finally 14 it . She hugged me with 15, saying thanks to me. I smiled and said it was nothing.

    Suddenly, I realized that helping someone was really something to me. I learned that giving from the heart doesn't 16 mean sacrifice and hard work. The 17 is finding something we love to do and finding someone who 18 that something. Our generosity can benefit others 19 ourselves. Once you have a good 20 of it, it's nothing. And it's really something.

某同学考试成绩不理想，老师安慰他说：“一次的失败不要紧，说不定，正是因为这次没考好，你才能及早发现问题，坏事也可能变成好事。”你知道老师引用了哪家的思想来教育学生的吗? （  ）