题干

如图2所示,一个物体在O点以初速度v开始作曲线运动,已知物体只受到沿x轴方向的恒力F作用,则物体速度大小变化情况是(       )
   

A:先增大后减小

B:先减小后增大

C:不断增大

D:不断减小

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答案(点此获取答案解析)

B

同类题2

阅读下面的文字,完成下列小题。

    说话并不是一件容易事。天天说话,不见得就会说话;许多人说了一辈子话,没有说好过几句话。所谓“辩士的舌锋”“三寸不烂之舌”等赞词,正是物以稀为贵的证据;文人们讲究“吐属”,也是同样的道理。我们并不想做辩士、说客、文人;但人生不外言动,除了动就只有言,所谓人情世故,一半儿是在说话里。一句话的影响,有时是你料不到的,历史和小说上有的是例子。

    说话即使不比作文难,也决不比作文容易。有些人会说话不会作文,但也有些人会作文不会说话。说话不是作文,不能够一个字一个字地推敲,因而不免有疏漏散漫的地方,不如作文的谨严。但那行云流水般的自然,却决非一般文章所及,是怎样一个不易达到的境界!我们的文章哲学里虽有“用笔如舌”这样一个标准,可是古今有几个人真能“用笔如舌”呢?

    我国人很早就讲究说话。《左传》《国策》《世说新语》是我们的三部说话的经典。一是外交辞令,一是纵横家言,一是清谈。你看他们的话多么婉转如意,句句字字打进人心坎里;还有一部《红楼梦》,里面的对话也极轻松、漂亮;此外汉代贾君房号为“语妙天下”,可惜留给我们的只有这一句赞词;明代柳敬亭的说书极有大名,可惜我们也无从领略;近年来的新文学,将白话文欧化,从外国文学中借用了许多活泼的、精细的表现,同时暗示我们将旧来有些表现重新咬嚼一番。这却给我们的语言一种新风味、新力量。这时期说话的艺术确有了相当的进步。论说话艺术的文字,从前著名的似乎只有韩非的《说难》,那是一篇剖析入微的文字。现在我们能够随口举出的例子就有俞平伯君的三篇《文训》和鲁迅君的《立论》,这些都是精警之作。

    我国人对于说话的态度,最高的是忘言,但也还免不了说话。其次是慎言,寡言,讷于言。这三样又有分别:慎言是小心说话,小心说话自然就少说话,少说话少出错儿;寡言是说话少,是一种深沉或贞静的性格或品德;讷于言是说不出话,是一种浑厚诚实的性格或品德。这两种多半是生成的。第三是修辞或辞令。至诚的君子,人格的力量照彻一切的阴暗;他用不着多说话,说话也无须修饰。只知讲究修饰,嘴边天花乱坠,腹中矛戟森然,那是所谓小人;他太会修饰了,倒教人不信了。他的戏法总有让人揭穿的一日。我们是介在两者之间的平凡的人,没有那伟大的魄力,可也不至于忘掉了自己。只是不能无视世故人情,我们看时候,看地方,看人,在礼貌与趣味两个条件之下,修饰我们的说话。这儿没有力,只有机智;真正的力不是修饰可得的。我们所能希望的只是:说得少,说得好。

(选自朱自清《说话》,有删改)

同类题4

阅读理解

    A cat is recovering in California after surviving a 6,500-mile journey across the Pacific stowed inside a Chinese shipping container without food or water. Staff and volunteers have named it “Ni Hao”, which is Chinese for “hello”.

    It was discovered breathing shallowly after a two-week trip across the Pacific Ocean. The cat was seriously suffering from loss of water and starvation when the container was opened in California last week, but was said to be doing well after being sent to the Carson Animal Care Centre in Los Angeles. At first it was too weak to stand, but finally took its first steps. Then it ate a good meal and slept soundly. The cat woke up on Thursday morning, physically in a better condition than 24 hours ago.

     “Ni Hao greeted the medical team with its first meow this morning and is attempting to stand,” said Marcia Mayeda, head of the Los Angeles Department of Animal Care and Control. Aaron Reyes, director of the Department, added, “We finally got to hear its voice. It sounds like a single-engine plane.”

    Ni Hao is expected to be observed for 60 days but afterwards animal workers will look forward to providing it with a good shelter. “It's much better for it to recover in a home environment,” Mr. Reyes said. “It's just like a human being in a hospital so we're hoping to move it.” He added, “Little by little we're getting there. We're hoping that under the treatment and with rest, it'll be able to recover quickly.”

    It was not immediately clear how the cat got into the container.