以下历史地图和图画反映的历史事实是 A．北击匈奴 B．文成公主入藏 C．汉通西

1路和4路公共汽车同时从阳光车站出发，1路公共汽车每隔6分钟发一次车，4路公共汽车每隔8分钟发一次车，这两路公共汽车同时出发以后，至少过多少分钟才第二次同时出发？

（14分）如图所示，一对磁偏转线圈形成的匀强磁场分布在R = 0.10m的圆形区域内,磁感应强度为0.1T。圆的左端跟y轴相切于直角坐标系的原点O，右端跟足够大的荧光屏MN相切于x轴上A点，置于原点的粒子源沿x轴正方向射出带正电的粒子流，以v =×10⁶m/s射入磁场，粒子的比荷为1×10⁸c/kg，重力不计。求

（1）粒子在磁场中运动的时间。

（2）粒子打在荧光屏上的位置距A的距离。

（3）要使粒子打不到荧光屏上，求粒子的速度大小应满足的条件。

阅读理解。

     If I were writing a history of my family, some of the darkest moments recorded would be those about

Christmas trees. One would certainly think otherwise; selecting and putting up our trees have always been

filled with risk. For example, one afternoon dangerously close to Christmas Eve my mother bought what

she thought to be a bargain, a glorious tree that was so full and tall that we could hardly get it into the house.

Once we did, my father immediately realized that we would have to hire a carpenter (木匠) to build a stand

for it. Another December, perhaps the very next one, we bought a tree earlier than we ever had before. We

were happy with its shape and delighted that its size was manageable. We easily placed it in a stand, decorated

(装饰) it from top to bottom, and then self-satisfiedly sat back by the fire in its soft light. Two or three days

passed and the truth could not be hidden; we had bought a tree cut so long ago that its needles were coming

off. There was nothing to do but undecorate it, take it down, and begin tree shopping again. Our most recent

Christmas tree offered still another difficult task. When we brought it home, once again it seemed larger than

it was in the great outdoors. To complicate matters, we had bought a new stand, one whose nuts (螺帽) and

bolts (闩子) worked more mysteriously than those of our old stands. I persuaded two young neighbors to stop

playing basketball and to help us get the tree into the house and set it correctly in the stand. Unfortunately, no

one noticed the mud on our helpers' shoes, so only after removing several reddish brown spots from the carpet

were we able to discuss the question of where the lights and ornaments (装饰物) were stored. Perhaps those

who cut their own trees have tales more painful than these. I don't care to hear them, as my family's

experiences are enough to cause me to make the following suggestion:"Let's forget the tree next Christmas.

Let's simply hang some flowers on the front door and over the mirror in the hall."

1. The darkest moments in the writer's family were with the fact that _____.

A. the family bought big Christmas trees

B. they had problems decorating their Christmas trees

C. they had problems picking suitable Christmas trees

D. they had problems finding carpenters for putting up Christmas trees

2. We can learn from the passage that the writer would like to _____.

A. forget about Christmas stories

B. get the neighbors to put up their trees

C. buy a better tree to celebrate Christmas

D. make other decorations rather than Christmas trees

3. When the writer said "my mother bought what she thought to be a bargain", he means _____.

A. she bought the tree at a cheap price

B. she didn't really want to buy it

C. she had to bargain hard with the salesman

D. she couldn't afford a more expensive one

4. Which of the following can be the best title for the passage?

A. How to Choose a Christmas Tree

B. No More Christmas Tree for Us

C. Dark Moments of Life

D. Christmas Without Trees

主材

秦汉雕塑的作用与成就是什么？