题干

在密闭容中发生下列反应aA(g)⇌cC(g)+dD(g),反应达到平衡后,将气体体积压缩到原来的一半,当再次达到平衡时,D的浓度为原平衡的1.8倍,下列叙述正确的是(  )

A:A的转化率变小

B:平衡向正反应方向移动

C:D的体积分数变大

D:a>c+d

上一题 下一题 0.0难度 选择题 更新时间:2013-03-22 05:08:33

答案(点此获取答案解析)

A

同类题1

阅读理解

    When kids believe they can achieve success in math and reading, they are more likely to achieve high test scores in those subjects, new research suggests.

    Researchers used one US data set (1,354 American children) and one UK data set (13,901 British children) to measure self-concept and standardized assessments of early and later academic achievement. Self-concept is how students perceive(感知)their abilities to succeed on academic tasks. The data involved youth aged 5 to 18.

    The study considered children's earlier achievement and their characteristics and backgrounds, including birth weight, race, gender, age, and their mother's education.

    The researchers found that children's self-concept of their ability in math predicted later math achievement, while their self-concept of their ability in reading predicted later reading achievement.

    The finding suggests that the links between self-concept of ability and later achievement are specific to areas; that is, there is a link from students' self-concept about reading to reading achievement, and from students' self-concept about math to math achievement.

     “It is not unusual to see standardized measures of achievement predict achievement later in schooling, but it shows that there is more to understand.” says study coauthor Pamela Davis-Kean.

    The research also showed that success was not limited to students who perform at the top levels.

     “It involves in students with different levels of achievement in math and reading,” says Maria Ines Susperreguy, an assistant professor at Pontificia Universidad Catolica de Chile, who led the study. “Even the lowest-performing students who had a more positive view of their math and reading abilities had higher levels of achievement in math and reading.”

    Researchers say they don't know what parents or students did to create these beliefs, but it's an issue they will research further.

同类题4

读阅读《我的母亲》选段,完成下面题目。
       ①但这九年的生活,除了读书看书之外,究竟给了我一点做人的训练。在这一点上,我的恩师就是我的慈母。
       ②每天天刚亮时,我母亲就把我喊醒,叫我披衣坐起。我从不知道她醒来坐了多久了。她看我清醒了,才对我说昨天我做错了什么事,说错了什么话,要我认错,要我用功读书。有时候她对我说父亲的种种好处,她说:“你总要踏上你老子的脚步。我一生只晓得这一个完全的人,你要学他,不要跌他的股。”(跌股便是丢脸、出丑。)她说到伤心处,往往掉下泪来。到天大明时,她才把我的衣服穿好,催我去上早学。学堂门上的锁匙放在先生家里;我先到学堂门口一望,便跑到先生家里去敲门。先生家里有人把锁匙从门缝里递出来,我拿了跑回去,开了门,坐下念生书。十天之中,总有八九天我是第一个去开学堂门的。等到先生来了,我背了生书,才回家吃早饭。
        ③我母亲管束我最严,她是慈母兼任严父。但她从来不在别人面前骂我一句,打我一下。我做错了事,她只对我一望,我看见了她的严厉眼光,就吓住了。犯的事小,她等到第二天早晨我睡醒时才教训我。犯的事大,她等到晚上人静时,关了房门,先责备我,然后行罚,或罚跪,或拧我的肉,无论怎样重罚,总不许我哭出声来。她教训儿子不是借此出气叫别人听的。
        ④有一个初秋的傍晚,我吃了晚饭,在门口玩,身上只穿着一件单背心。这时候我母亲的妹子玉英姨母在我家住,她怕我冷了,拿了一条小衫出来叫我穿上。我不肯穿,她说:“穿上吧,凉了。”我随口回答:“娘(凉)什么!老子都不老子呀。”我刚说了这句话,一抬头,看见母亲从家里走出,我赶快把小衫穿上。但她已听见这句轻薄的话了。晚上人静后,她罚我跪下,重重地责罚了一顿。她说:“你没了老子,是多么得意的事!好用来说嘴!”她气得坐着发抖,也不许我上床去睡。我跪着哭,用手擦眼泪,不知擦进了什么微菌,后来足足害了一年多的眼翳病。医来医去,总医不好。我母亲心里又悔又急,听说眼翳可以用舌头舔去,有一夜她把我叫醒,她真用舌头舔我的病眼。这是我的严师,我的慈母。