小明同学做了“做观察水沸腾”的实验。 (1)实验中为了减少实验时间,可采取什么措

题型:实验题

问题:

小明同学做了“做观察水沸腾”的实验。

(1)实验中为了减少实验时间,可采取什么措施:______________________;(只写一种)

(2)当水温接近90℃时,每隔1min记录一次温度, 表格如下:

此时水的沸点是____,水沸腾过程中特点是_______________。

考点:液化现象、方法及其应用汽化及汽化的特点
题型:实验题

如图所示,真空中有一个半径为R,质量分布均匀的玻璃球,频率为γ的细光束的真空中沿直线BC传播,并于玻璃球表面的C点经折射进入玻璃球,并在玻璃球表面的D点又经折射进入真空中,已知∠COD=120°,玻璃球对该激光的折射率为

3
,则下列说法中正确的是(  )

A.一个光子在穿过玻璃球的过程中能量逐渐变小

B.改变入射角α的大小,细激光束可能在玻璃球的内表面发生全反射

C.此激光束在玻璃中穿越的时间为t=3R/c(c为真空中的光速)

D.激光束的入射角为α=45°

题型:实验题

创作出著名油画肖像《英诺森十世》的画家委拉斯凯兹是______人。

A.西班牙
B.法国
C.意大利
D.英国

题型:实验题

Teachers need to be aware of the emotional, intellectual, and physical changes that younga-duhs experience. And they also need to give serious (91) to how they can best (92) such changes. Growing bodies need movement and (93) , but not just in ways that emphasize competition. (94) they are adjusting to their new bodies and a whole host of new intellectual and emotional challenges, teenagers are especially self-conscious and need the (95) that comes from achieving success and knowing that their accomplishments are (96) by others. However, the typical teenage lifestyle is already filled with so much competition that it would be (97) to plan activities in which there are more winners than losers, (98) , publishing newsletters with many student-written book reviews, (99) student artwork, and sponsoring book discussion clubs. A variety of small clubs can provide (100) opportunities for leadership, as well as for practice in successful (101) dynamics. Making friends is extremely important to teenagers, and many shy students need the (102) of some kind of organization with a supportive adult (103) visible in the background.
In these activities, it is important to remember that young teens have (104) attention spans. A variety of activities should be organized (105) participants can remain active as long as they want and then go on to (106) else without feeling guilty and without letting the other participants (107) This does not mean that adults must accept irresponsibility. (108) , they can help students acquire a sense of commitment by (109) for roles that are within their (110) and their attention spans and by having clearly stated rules.

A.assistance

B.guidance

C.confidence

D.tolerance

题型:实验题

交通部《公路工程施工招标管理办法》规定,中标者向招标单位提交的履约保函的金额为合同总价的5%~10%。 ( )

题型:实验题

汇编目录由()组成。

A、顺序号

B、名目

C、注释号

D、页码

更多题库