当乌苏里江上旭日东升时，帕米尔高原还是繁星满天，这种现象的原因是（ ） A．我国

如图（a）所示，两根足够长的水平平行金属导轨相距为L=0.5m，其右端通过导线连接阻值R=0.6Ω的电阻，导轨电阻不计，一根质量为m=0.2kg、阻值r=0.2Ω的金属棒ab放在两导轨上，棒与导轨垂直并保持良好接触，金属棒与导轨间的动摩擦因数μ=0.5．整个装置处在竖直向下的匀强磁场中，取g=10m/s²．若所加磁场的磁感应强度大小恒为B，通过小电动机对金属棒施加水平向左的牵引力，使金属棒沿导轨向左做匀加速直线运动，经过0.5s电动机的输出功率达到P=10W，此后电动机功率保持不变．金属棒运动的v～t图象如图（b）所示，试求：

（1）磁感应强度B的大小；

（2）在0～0.5s时间内金属棒的加速度a的大小；

（3）在0～0.5s时间内电动机牵引力F与时间t的关系；

（4）若在0～0.3s时间内电阻R产生的热量为0.15J，则在这段时间内电动机做的功．

致畸最敏感的时期是胚胎发育的（）

A.1～2周

B.3～8周

C.9～11周

D.12～20周

E.20～24周

阅读理解

     Free On-line Short Stories For Kids: Trevor The Taxi

     In this children's story, suited to younger children, we have an adventure with Trevor. He is a taxi.

Trevor loves his life:

     'Sometimes he takes patients to the nursing home, where they can get better after being ill, and

sometimes he takes people home when they have been shopping, and Stan puts all their packages inside

Trevor's boot, so they will not get wet or broken.'

     The black cab, in this adventure, goes far beyond the call of duty whilst he achieves his wildest dreams!  What could this be? Well you will just have to read this short story for yourself!

     Free On-line Short Stories For Kids: The Girl Who Believed In Fairys

     The fairy queen is upset and the elves just don't know what to do:

     '"Oh dear, oh dear," sobbed the queen, getting her hankie all wet with her constant crying. For the

twelfth time that day, Elgie the chief elf took her hankie and wrung it out on to the carpet of grass that

grew all around the palace.'

     How will they manage to help the queen? Why was she so unhappy? There is only one person that

can help! Can she do it? This is a lovely fairy tale that will glow the embers of your heart - only for young

little princesses!

    Free On-line Short Stories For Kids: The Envious Kings

     This story is suitable for 6 years and upwards.

     Unfolding in the story pages of this recommendation is a children's story about two envious kings

who were competing with each other:

     'In spite of the easy life that the two kings had, they were not happy, for each of them kept thinking

that the other one had a bigger and better palace, or owned more horses, or had more jewels or even

had creamier milk.'

     They were both petty and, through their envy, they caused themselves much trouble. Who do you

think saved the day? Well, you will just have to read the story to find out!

    Free On-line Short Stories For Kids: The Wise Old Woman

     This story is probably suited to the 8 year old age range and upwards, although would appeal to

adults, alike.

     Here I introduce you to one of my kids on-line stories listed on the writing and literature section of

Hubpages. In this parable you will find a magical world of wisdom involving trees, people and someone

very special.

    'As she stood and watched, the knowledge melted into her and the sapling grew...The magical

transition took her breath away and as she watched on with ore, she noticed something strange.'

So, what was this strangeness and magical transition? Let me leave you with wonderment ... and a

click of the link!

     Free On-line Short Stories For Kids: Unusual Stories - Faffenburger's Odyssey

     This story is probably more suited to the older child. So who is Faffenburger? Well with one of these

free on-line short stories for kids, we enter into a different realm. A world of nonsense as Faffenburger

moves within alpha and omega. This is a rather unusual story as you will find out!

     'My friend, Henry Faffenburger stomped down the long lane on his short stumpy legs, moonlight

glancing off his bald-spot, which was a little surprising as there was no moon that night. As he rounded

the bend, he saw a pair of headlights coming toward him. They drew level, and stopped. A small man

with yellow eyes emerged from the darkness behind the lights, and enquired if Faffenburger would like

a lift.

     "Where are you going ?" asked my friend. "Wherever you want to go", replied the owner of the

yellow eyes.'

     So, the adventure begins! Where will they go? Alpha, Omega or just the middle? After all, it was a

long summer - especially the middle! Take a closer look at this - you might find something a little more

strange and a little more hidden that you have noticed before. Intrigued? Well you should be with

Faffenburger's Odyssey!

1.This passage gives us information about ________?

A. Story books for adults  

B. On-line stories for adults 

C. Story books for children

D. On-line stories for children

2.Which story is more suitable for the older children?

A.Trevor The Taxi

B.Faffenburger's Odyssey

C.The Wise Old Woman

D.The Envious Kings

3.You can find the character "queen" in__________?

A.The Envious Kings

B.The Girl Who Believed In Fairys

C.The Wise Old Woman

D.Trevor The Taxi

4.Who will find the passage useful?

A.parents with children

B. children who loves stories

C. teachers in high school

D. experts who concern children

5. According to the passage, the kings in "The Envious Kings" can be described as_______?

A..envious

B. powerful

C. rude

D. ugly

民间统计的特点有______。

A．义务性

B．自愿性

C．强制性

D．公益性

E．营利性

火灾报警控制器按其作用分类，可分为（）。

A、区域火灾报警控制器

B、集中火灾报警控制器

C、通用火灾报警控制器