题干

关于速度和加速度的关系,下列说法正确的是(   )

A:若物体加速度越来越大,则其速度一定越来越大

B:若某时刻物体速度为零,则此刻它的加速度也一定为零

C:加速度总与速度变化的方向相同

D:作直线运动的物体,若加速度与规定的正方向相反,则物体速度一定在变小

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答案(点此获取答案解析)

C

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    “Clothes Swapping”has become an increasingly popular activity for women in the United States. The women can give away unwanted clothing at a clothes swap event and get something different in return.

    Recently about 300 women went to a clothes swap at a high school in Springfield, Virginia. It was the largest crowd ever for the area's popular clothing-swapping group.

    Daphne Steinberg was having a good day.“For anyone who knows Ann Taylor LOFT, Ann Taylor is a really nice women's designer and I will totally wear this to work. So I love that, I love that I can equip myself for work, have a good time in doing it, not totally bankrupt myself.”

    Sandy Van Dusen likes the idea that clothes are finding new homes instead of being thrown away. “Because it helps to keep the Earth green. There's no point in my opinion in continuing to buy new clothes when we can reuse what's already here. Give it a new home--- let somebody else love what you used to love and no longer love.”

    Kim Pratt organized the clothing-swapping event in Springfield. She also organized a money-raising activity for the high school's debate team. It is one of several ways that her group gives to charitable causes. Another is by donating all of the“un-swapped” clothing to shelters for victims of domestic violence.

    “I started doing this four years ago, and we've been doing it for four years, getting bigger and bigger each time we have a swap.”

    She used the social media website meetup.com to help publicize the events. The website has helped her group grow from 30 members to 1,300. Mrs.Pratt says most of the members respect the clothing swap rules. But she say competition for desirable fashion can be strong.

    “We have to tell people sometimes not to hover over the new people coming in with their clothing. As they put it out, some people tend to grab the stuff right out of their hands and it becomes like a free-for-all. We try to avoid that as much as possible.”