历史学家徐中约说：“根据一位美国著名科学家的研究，1960年时中国的25万科学家和工程师中，有90%是在1949年中国人民共和国成立后培养出来的，而在1960年，中国工科毕业生数量大约是美国工科毕业生的75%。”对此现象的合理解释是(      )

    My mom works on Saturdays, so every Saturday my aunt, Jenny, takes me somewhere interesting. For example, once she took me to the sea museum, and then she made me do a project (专题研究) about my favorite 1 .

    Last Saturday, Jenny took me to an old people's home. She was a volunteer (志愿者) there, so she 2 went there in her free time. There were a lot of old People there. Jenny introduced (介绍) 3 to some of them. Then she asked me if I would like to read the newspaper to them. I was glad to do that. I read 4 so they could hear me. They said my reading was excellent. I felt really 5 .

    Later, Jenny and I had lunch with them. I sat at a table with one man and two women. During lunch, they told me stories 6 their lives. The man had been a guide. The two women were from other 7  Mrs. Wang came from China, and Mrs. Guleed was from South Africa. They 8 their lives in their hometowns. It sounded different.

    After lunch, Jenny 9 the piano. Some of the people sang along to the music. The people there were very kind to me. I liked them so much that I began to 10 them as Soon as I got home.

掷两枚质地均匀的骰子，其点数之和大于10的概率为____．