如图,竖直绝缘墙上固定一带电小球A,将带电小球B用轻质绝缘丝线悬挂在A的正上方C

题型:填空题

问题:

如图,竖直绝缘墙上固定一带电小球A,将带电小球B用轻质绝缘丝线悬挂在A的正上方C处,图中AC=h。当B静止在与竖直方向夹角方向时,A对B的静电力为B所受重力的倍,则丝线BC长度为        。若A对B的静电力为B所受重力的0.5倍,改变丝线长度,使B仍能在处平衡。以后由于A漏电,B在竖直平面内缓慢运动,到处A的电荷尚未漏完,在整个漏电过程中,丝线上拉力大小的变化情况是        。

考点:共点力的平衡
题型:填空题

I will never forget the year I was about twelve years old. My mother told us that we would not be (16) Christmas gifts because there was not enough money. I felt sad and thought, "What would I say when the other kids asked what I’ d (17) " Just when I started to (18) that there would not be a Christmas that year, three women (19) at our house with gifts for all of us. For me they brought a doll. I felt such a sense of (20) that I would no longer have to be embarrassed when I returned to school. I wasn’t (21) . Somebody had thought (22) of me to bring me a gift.

Years later, when I stood in the kitchen of my new house, thinking how I wanted to make my (23) Christmas there special and memorable, I (24) remembered the women’s visit. I decided that I wanted to create that same feeling of (25) for as many children as I could possibly reach.

So I (26) a plan and gathered forty people from my company to help. We gathered about 125 orphans (孤儿) at the Christmas party. For every child, we wrapped colorful packages filled with

toys, clothes, and school supplies, (27) with a child’ s name. We wanted all of them to know they were (28) Before I called out their names and handed them their gifts, I (29) them that they couldn’t open their presents (30) every child had come forward. Finally the (31) they had been waiting for came as I called out, "One, two, three. Open your presents!" As the children opened their packages, their faces beamed and their bright smiles (32) up the room. The (33) in the room was obvious, and (34) wasn’ t just about toys. It was a feeling, and the feeling I knew (35) that Christmas so long ago when the women came to visit. I wasn’t forgotten. Somebody thought of me. I matter.

26().

A. kept up with

B. caught up with

C. came up with

D. put up with

题型:填空题

7.6和7.60大小相等,计数单位也相同.______(判断对错)

题型:填空题
冬天,家中使用的红外线取暖器,看起来它发出淡红色的光,这是因为(   )
A.红外线本身就是一种淡红色的光

B.红外线中有一部分是看得见的,有一部分是看不见的,看得见的那一部分是淡红色的

C.这种取暖器根本就没有发出红外线

D.电取暖器温度较高,在发出红外线的同时还发出少量的红光,红外线本身是不可见的

题型:填空题

四川菜中的软炸酥方应跟用花椒盐、生菜、葱、()味碟。

题型:填空题

在机床型号XK714中,XK的含义是()

A.数控机床

B.数控铣床

C.数控车床

D.加工中心

更多题库