题干

跳伞运动员在空中匀速降落时机械能将(   )

A:逐渐减少  

B:逐渐增大

C:保持不变  

D:无法说明机械能的变化情况

上一题 下一题 0.0难度 选择题 更新时间:2017-08-04 09:10:38

答案(点此获取答案解析)

A

同类题2

阅读下面的文言文,完成下列各题。

    徐谊,字子宜,一字宏父,平阳人。乾道八年进士,累官太常丞。孝宗临御久,事皆上决,执政惟奉旨而行,群下多恐惧顾望。谊谏曰:“若是则人主日圣,人臣日愚,陛下谁与共功名乎?”及论乐制,谊对曰:“宫乱则荒,其君骄;商乱则陂,其官坏。”上遽改容曰:“卿可谓不以官自惰矣。”

    知徽州,陛辞,属光宗初受禅,谊奏:“三代圣王,有至诚而无权术,至诚不息,则可以达天德矣。”至郡,歙县有妻杀夫系狱,以五岁女为证,谊疑曰:“妇人能一掌致人死乎?”缓之未覆也。会郡究实税于庭,死者父母及弟在焉,乃言:“我子欠租久系,饥而大叫,役者批之,堕水死矣。”然后冤者得释,吏皆坐罪,阖郡以为神。

    孝宗疾浸棘上久稽定省谊入谏退告宰相曰上慰纳从容然目瞪不瞬意思恍惚真疾也宜祷祠郊庙进皇子嘉王参决丞相留正不克用。

    孝宗崩,上不能丧。谊与少保吴琚议,请太皇太后临朝,扶嘉王代祭。及将禫,正忧惧,仆于殿庭而去。谊以书谯赵汝愚曰:“自古人臣为忠则忠,为奸则奸,忠奸杂而能济者,未之有也。”汝愚问策安出,谊曰:“此大事,非宪圣太后命不可。而知阁门事韩侂胄,宪圣之戚也,同里蔡必胜与侂胄同在阁门,可因必胜招之。”侂胄至,汝愚以内禅议遣侂胄请于宪圣,侂胄因内侍达汝愚意,宪圣许之。

    宁宗即位,侂胄恃功,以赏薄浸觖望。谊告汝愚曰:“异时必为国患,宜饱其欲而远之。”不听。

    汝愚雅器谊,除授建明多咨访,谊随事裨助,不避形迹,怨者始众。尝劝汝愚早退,汝愚亦自请。侂胄疑将排己,首谒谊,退束装,冀谊还谒,留之通殷勤,谊不往。

    初,金攻庐、楚不下,留兵缀濠州以待和,时时钞掠,淮人大惊。谊昼夜拊循,益严备御。朝廷惧生事,移知隆兴府以卒,后谥忠文。

(《宋史•列传一五六》)

【注释】觖:不满意。

同类题5

请认真阅读下面短文,并根据短文内容回答问题。
      Do you feel lonely when your best friend isn't around? Here's our advice to you ---and to all kids who feel lonely sometimes. 
It's hard when a best friend isn't around --- maybe because he or she moved to a different school or a different class. You may feel left out at break or lunchtime. You want to have new friends, but how do you make them? Maybe it seems everybody else already has his or her friends. But remember, there's always room for more friends.
      Start by looking around your classroom --- think about which kids you'd like to play with at break. Look for chances to say hi to them, smile, and be friendly. Offer to share something or express your appreciation (欣赏) to them. Invite someone to play with you or say, “Do you want to sit here?”in the lunchroom. When you're at break, walk over to kids you want to play with, act friendly, and say “Hi, can I play, too?” or just join in. 
     If you have trouble doing this or if you're feeling shy, ask your teacher to help you make new friends. Teachers are usually pretty good at matching up friends. The best way to make friends is to be a friend. Be kind, be friendly, share, say nice things, offer to help ---and pretty soon, you'll have one, or two, or even more new friends.
     You might still miss that special best friend. But when you see each other, you can share something you didn’t have before he or she left. You can introduce him or her to your new friends!
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