题干

判断水中生活的动物是否属于鱼类的主要依据是(  )

A:能在水中游泳

B:身体内有鳔

C:有鳍,用鳃呼吸

D:能在水中呼吸

上一题 下一题 0.0难度 选择题 更新时间:2018-06-19 12:22:23

答案(点此获取答案解析)

C

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    Weekend gym rats might be onto something. Weekend warriors, who put recommended amounts of exercise into one or two gym sessions(时段), experience similar health benefits to those who work out several times a week, according to a new study. And those benefits include a longer life. “It is encouraging news that working out in just one or two days per week is connected to a lower risk of demise, even among people who do some activities but don't quite meet recommended exercise levels,” the lead researcher Emmanuel Stamatakis says in a statement.

    The World Health Organization recommends that adults perform two and a half hours of moderate-intensity(中等强度的)physical exercise, or an hour and 25 minutes of more energetic exercise per week. Usually this is done within several days, with experts suggesting that adults get up to 30 minutes of regular exercise each day. However, the new study suggests that busy people may be able to meet the standards when they have more free time, such as at weekends, and stay healthy all the same.

    Researchers studied data from more than 63,000 men and women in England and Scotland, including data about their activity habits and risks for death. The researchers put each individual in one of four groups: those who described themselves as inactive, those who exercised but less than what was recommended, those who exercised in the “weekend warrior” style, and those who worked out regularly more than three days a week.

    Adults who exercised in the “weekend warrior” style had a 40 percent lower risk of cardiovascular(心血管的)disease and a 30 percent lower risk of death by any cause than those who did not exercise at all. The lower risks of cardiovascular disease and overall death were similar to the risks of people who worked out regularly over the week.

    But take a pause before you give up your weekday gym habit. Just a couple of light sessions won't be enough to get benefits: “Weekend warrior” exercise sessions are usually 75-minute energetic workouts, according to the study.

    The results are promising overall, if you just simply can't fit physical activities into most days. The key here is that exercise is truly a lifeline(救生索): It reduces your risk of illnesses like heart disease, diabetes, cancer and depression, according to the WHO. So, if you are just too busy on weekdays, let go of the guilt(内疚). Just make sure to hit the gym hard at weekends.

同类题4

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日  子

陈忠实

    两架罗筛,用木制三脚架撑住,斜立在掏挖出湿漉漉的沙石的大坑里。男人一把镢头一把铁锨,女人也使用一把镢头一把铁锨;男人有两只铁丝编织的铁笼和一根扁担,女人也配备着两只铁丝编成的铁笼和一根扁担。

    我回到乡下的第一天,走到滋水河边发现了河对面的这一对夫妇。就我目力所及,上游和下游的沙滩上,支着罗网埋头这种劳作的再没有第二个人了。

    早春中午的太阳已见热力,晒得人脸上烫烫的,却很舒服。

    “你该到城里找个营生干,”我说,“你是高中生,该当……”

    “找过。也干过。干不成。”男人说。

    “一家干不成,再换一家嘛!”我说。

    “换过不下五家主儿,还是干不成。”女人说。

    “工作不合适?没找到合适的?”我问。

    “有的干了不给钱,白干了。有的把人当狗使,喝来喝去没个正性。受不了啊!”他说。

    “那是个硬熊。想挣人家钱,还不受人家白眼。”她说。

    “不是硬熊软熊的事。出力挣钱又不是吃舍饭。”他说。

    “凭这话,老陈就能听出来你是个硬熊,”女人说,“他爷是个硬熊。他爸是个硬熊。他还是个不会拐弯的硬熊——种系的事。”

    “中国现时啥都不缺,就缺硬熊。”他说。

    “弓硬断弦。人硬了……没好下场。”她说。

    “这话倒对。俺爷被土匪绑在明柱上,一刀一刀割。割一刀问一声,直到割死也不说银圆在哪面墙缝里藏着。俺爸被斗了三天两夜,不给吃不给喝不准眨眼睡觉直到昏死,还是不承认‘反党’……我不算硬。”

    “你已经硬到只能挖石头咧!你再硬就没活路了。硬熊——”

    他很坦率又不无迷津地悄声对我说,他也搞不清自己为什么偏偏注意女人的腰,一定要娶一个腰好的媳妇,脸蛋嘛倒在其次,能看过去就行了。

    他大声慨叹着,不无讨好女人的意思:“农村太苦太累,再好的腰都给糟践了。”

    男人把堆积在罗网下的石子铲进笼里,用扁担挑起来,走上沙坑的斜坡,木质扁担吱呀吱呀响着,把笼里的石头倒在石堆上。折返身回来,再装再挑。女人对我说:“他见了你话就多了。他跟我在这儿,整晌整晌不说一句话。”

    太阳沉到西原头的这一瞬,即将沉落下去的短暂的这一瞬,真是奇妙无比景象绚烂的一瞬。泛着嫩黄的杨柳林带在这一瞬里染成橘红。河岸边刚刚现出绿色的草坨子也被染成橘黄色。小木桥上的男人和女人被这瞬间的霞光涂抹得模糊了,男女莫辨。

    应办了几件公务,再回到滋水河的时候,小麦已经吐穗了。

    我有点急迫地赶回乡下老家来,就是想感受小麦吐穗扬花这个季节的气象。

    女人正挥动铁锨朝罗网上抛掷着沙石。男人呢?

    “那位硬熊呢?”“没来。”

    我问:“咋咧?出什么事了?”

    她停住手中的铁锨,重重地深深地吁出一口气:“女儿考试没考好。”

    “就为这事?”我也舒了一口气,“这回没考好,下回再争取考好嘛!”

    “这娃娃也是……平时学得挺好的,考试分数也总排前头。偏偏到分班的节骨眼上,一考就考……”

    “直到昨日晚上,他才说了一句话:我现在还捞石头做啥!我还捞这石头做啥……”

    “你不是说他是个硬熊吗?这么一点挫折就软塌下来了?”我说。

    “他高考考大学差一点点分数没上成,指望娃能……”

    “他来了!天哪!他自个儿来了——”

    我听见女人的抖声,也看见她随着颤颤的抖声涌出的眼泪。

    我瞬即看见他正向这边的沙梁走来。

    他的肩头背着罗网,扛着镢头铁锨,另一只肩头挑着担子,两只铁丝编织的铁笼吊在扁担的铁钩上。

    他对我淡淡地笑笑。

    他开始支撑罗网。

    “天都快黑咧,你还来做啥?”她说。

    “挖一担算一担嘛。”他说。

    许久,他都不说话。镢头刨挖沙层在石头上撞击出刺耳的噪声,偶尔迸出一粒火星。

    许久,他直起腰来,平静地说:“大不了给女儿在这沙滩上再撑一架罗网喀!”

    我的心里猛然一颤。

    我看见女人缓缓地丢弃了铁锨。我看着她软软地瘫坐在湿漉漉的沙坑里。我看见她双手捂住眼睛垂下头。我听见一声压抑着的抽泣,

    我的眼睛模糊了。