有三个阻值分另为R1=10Ω，R2=20Ω，R3-80Ω的电阻。若实验时需要一个阻值为16Ω的电阻，以下是从这三个电阻中选用两个进行连接，能满足实验要求的是
| A．R1和R2并联 | B．R2和R3并联 | C．R1和R2串联 | D．R1和R3串联 |
现在家庭电器化程度越来越高，用电安全是一个十分突出的问题，下表提供了一组部分人的人体电阻平均值数据：
（1）从表中可以看出干燥时电阻大约是潮湿时电阻的_______倍。
（2）在表格中的空格处填入人体潮湿时加220V电压后的电流值；
（3）若对人的安全电流是25mA以下，上述哪几项是十分危险的？
__________________________________________________________
（4）请你谈谈：在生活中，作为中学生安全用电的注意事项（说出一条就行）
__________________________________________________________
| 测量项目 | 完全干燥时 | 潮湿时 | ||
| | 电阻 | 电流（加220V） | 电阻 | 电流（加220V） |
| 手与手之间 | 200KΩ | 1.1×10-3A | 5KΩ | |
| 手与脚之间 | 300KΩ | 7.3×10-4A | 8KΩ | |
| 手与塑料鞋底之间 | 400KΩ | 5.5×10-4A | 10KΩ | |
（2）在表格中的空格处填入人体潮湿时加220V电压后的电流值；
（3）若对人的安全电流是25mA以下，上述哪几项是十分危险的？
__________________________________________________________
（4）请你谈谈：在生活中，作为中学生安全用电的注意事项（说出一条就行）
__________________________________________________________
A metaphor is a poetic device that deals with comparison. It compares similar qualities of two dissimilar objects. With a simple metaphor, one object becomes the other: Love is a rose. Although this does not sound like a particularly rich image, a metaphor can communicate so much about a particular image that poets use them more than any other type of figurative language(修辞). The reason for this is that poets compose their poetry to express what they are experiencing emotionally at that moment. Consequently, what the poet imagines love to be may or may not be love we see it. Therefore, the poet’s job is to enable us to experience it, to feel it the same way as the poet does.
Let’s analyze this remarkably unsophisticated metaphor concerning love and the rose to see what it offers. Because the poet uses a comparison with a rose, first we must examine the characteristics of that flower. A rose is spectacular in its beauty; its petals(花瓣) are nicely soft, and its smell is pleasing. It’s possible to say that a rose is actually a feast to the senses of sight, touch, and smell. The rose’s appearance seems to border on(近似于)perfection, each petal seemingly symmetrical(对称的) in form. Isn’t this the way one’s love should be? A loved one should be a delight to one’s senses and seem perfect. However, there is another dimension added to the comparison by using a rose. Roses have thorns(刺). The poet wants to convey the idea that roses can be tricky(机警的). So can love, the metaphor tells us. When one reaches out with absolute trust to touch the object of his or her affection, ouch, a thorn can cause great harm! “Be careful,” the metaphor warns: Love is a feast to the senses, but it can overwhelm us, and it can also hurt us and cause acute suffering. This is the poet’s perception of love--a warning. What is the point? Just this: It took almost 14 sentences to clarify what a simple metaphor communicates in only four words! That is the artistry and the joy of the simple metaphor.
【小题1】According to the passage, what is a metaphor?
【小题2】 The main idea of this passage is that .
【小题3】 It can be inferred from the passage that a metaphor is .
【小题4】 As is meant by the author, thorns of a rose_________.
【小题5】 The meaning of the love-is–a-rose metaphor is that____________-
Let’s analyze this remarkably unsophisticated metaphor concerning love and the rose to see what it offers. Because the poet uses a comparison with a rose, first we must examine the characteristics of that flower. A rose is spectacular in its beauty; its petals(花瓣) are nicely soft, and its smell is pleasing. It’s possible to say that a rose is actually a feast to the senses of sight, touch, and smell. The rose’s appearance seems to border on(近似于)perfection, each petal seemingly symmetrical(对称的) in form. Isn’t this the way one’s love should be? A loved one should be a delight to one’s senses and seem perfect. However, there is another dimension added to the comparison by using a rose. Roses have thorns(刺). The poet wants to convey the idea that roses can be tricky(机警的). So can love, the metaphor tells us. When one reaches out with absolute trust to touch the object of his or her affection, ouch, a thorn can cause great harm! “Be careful,” the metaphor warns: Love is a feast to the senses, but it can overwhelm us, and it can also hurt us and cause acute suffering. This is the poet’s perception of love--a warning. What is the point? Just this: It took almost 14 sentences to clarify what a simple metaphor communicates in only four words! That is the artistry and the joy of the simple metaphor.
【小题1】According to the passage, what is a metaphor?
| A．A comparison between two different objects with similar features. |
| B．A contrast between two different things to create a vivid image. |
| C．A description of two similar objects in a poetic way. |
| D．A literary device specially employed in poetry writing. |
| A．rose is a good image in poetry | B．love is sweet and pleasing |
| C．metaphor is ambiguous | D．metaphor is great poetic device |
| A．difficult to understand | B．rich in meaning | C．not precise enough | D．like a flower |
| A．protect the rose from harm | B．symbolize reduced love |
| C．add a new element to the image of love | D．represent objects of one’s affection |
| A．love is a true joy | B．true love comes once in a lifetime |
| C．love does not last long | D．love is both good and bad experiences |
电热饮水机有加热和保温两种工作状态（由机内温控开关S0自动控制），从说明书上收集到如下数据及如图所示的电路原理图。
（1）请分析说明温控开关S0断开时，饮水机处于哪种工作状态？
（2）求电阻R1的阻值；
（3）求电热饮水机在加热状态下的工作电流。
| 热水箱容量 | 2L |
| 额定电压 | 220V |
| 加热时的功率 | 400W |
| 保温时的功率 | 40W |
（1）请分析说明温控开关S0断开时，饮水机处于哪种工作状态？
（2）求电阻R1的阻值；
（3）求电热饮水机在加热状态下的工作电流。
汽车、拖拉机的发动机常用水做冷却剂．是因为水具有
0 65672 65680 65686 65690 65696 65698 65702 65708 65710 65716 65722 65726 65728 65732 65738 65740 65746 65750 65752 65756 65758 65762 65764 65766 65767 65768 65770 65771 65772 65774 65776 65780 65782 65786 65788 65792 65798 65800 65806 65810 65812 65816 65822 65828 65830 65836 65840 65842 65848 65852 65858 65866 235360
| A．较小的密度 | B．较大的比热容 |
| C．较低的凝固点 | D．较高的沸点 |