题干

在三棱柱ABC-A1B1C1中,各棱长相等,侧棱垂直于底面,点D是侧面BB1C1C的中心,则AD与平面BB1C1C所成的角的大小是(         )

A:30°

B:45°

C:60°

D:90°

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C

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    The Sixth Time I Went to the Principal's Office

    When I was in the seventh grade, I had problems behaving. My heart was in the right place, but I couldn't always follow the rules. I played many tricks on my schoolmates. Once, I even pulled a girl's hair on the school bus to get her attention. As a result, I was repeatedly sent to the office of the principal(校长).

    Although I hated going there, I did not hate the principal, Mr. Ratcliff. Mr. Ratcliff was a kind, elderly man. When he spanked( 打屁股) me for putting some ants into a classmate's pencil box, it didn't hurt at all, but it did hurt my feelings. I thought so much of him and moments like that seemed to prove I was hopelessly bad.

    When I got called to Mr. Ratcliff's office for the sixth time, I had no idea what I had done. I felt disappointed as I walked down there. I went into his office, sat down, and looked at the floor. Then he said the last thing I expected to hear:” Kevin, I've heard you've been behaving really well lately. I want you to know how proud I am of you, and I just called you down to my office to give you a peppermint.”

    “Really?” I was surprised.

    “Yes. Now you can take that peppermint and go back to class.”

    I carried the peppermint with me as if it was a gold coin. When I got into my classroom, I bragged ( 吹嘘) to my classmates about my turnaround, excitedly. I wasn't so bad after all.

    Mr. Ratcliff was really kind. He made me realize that I was just a kid who had problems with behavior. He bought some peppermints and took the time to notice me when I got something—anything—right. Mr. Ratcliff gave me some hope by giving me some love. I will just remember him for the rest of my life.