题干

下列化学实验操作或事故处理方法正确的是

A:为了节约,应将所有实验过程中取用的剩余药品放回原试剂瓶

B:做蒸馏实验时,应使温度计水银球位于蒸馏烧瓶支管口处

C:油或酒精着火时都可以用水扑灭

D:浓硫酸溅到皮肤上时,立即用大量水冲洗然后用3%~5%的NaHCO3溶液洗。

上一题 下一题 0.0难度 选择题 更新时间:2018-10-28 11:14:15

答案(点此获取答案解析)

B

同类题3

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.