题干

在冬奥会短道速滑项目中,运动员绕周长仅111米的短道竞赛.运动员比赛过程中在通过弯道时如果不能很好地控制速度,将发生侧滑而摔离正常比赛路线.图中圆弧虚线Ob代表弯道,即运动正常运动路线,Oa为运动员在O点时的速度方向(研究时可将运动员看作质点).下列论述正确的是(   )

A:发生侧滑是因为运动员受到的合力方向背离圆心

B:发生侧滑是因为运动员受到的合力大于所需要的向心力

C:若在O发生侧滑,则滑动的方向在Oa左侧

D:若在O发生侧滑,则滑动的方向在Oa右侧与Ob之间

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D

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    When her five daughters were young, Helen An always told them that there was strength in unity (团结). To show this, she held up one chopstick, representing one person. Then she easily broke it into two pieces. Next, she tied several chopsticks together, representing a family. She showed the girls it was hard to break the tied chopsticks. This lesson about family unity stayed with the daughters as they grew up.

    Helen An and her family own a large restaurant business in California. However, when Helen and her husband Danny left their home in Vietnam in 1975, they didn't have much money. They moved their family to San Francisco. There they joined Danny's mother, Diana, who owned a small Italian sandwich shop. Soon afterwards, Helen and Diana changed the sandwich shop into a small Vietnamese restaurant. The five daughters helped in the restaurant when they were young. However, Helen did not want her daughters to always work in the family business because she thought it was too hard.

    Eventually the girls all graduated from college and went away to work for themselves, but one by one, the daughters returned to work in the family business. They opened new restaurants in San Francisco and Los Angeles. Even though family members sometimes disagreed with each other, they worked together to make the business successful. Daughter Elizabeth explains, “Our mother taught us that to succeed we must have unity, and to have unity we must have peace. Without the strength of the family, there is no business.”

    Their expanding business became a large corporation in 1996, with three generations of Ans working together. Now the Ans' corporation makes more than $ 20 million each year. Although they began with a small restaurant, they had big dreams, and they worked together. Now they are a big success.