两个相同的可视为质点的小球A和B，质量均为m，用长度相同的两根细线把A，B两球悬挂在水平天花板上的同一点O，并用长度相同的细线连接A，B两个小球，然后，用一水平方向的力F作用在小球A上，此时三根线均处于伸直状态，且OB细线恰好处于竖直方向如图所示．如果两小球均处于静止状态，则力F的大小为（   ）

– ____ your new job _____, Jim?

– Well, it is usually full of fun. But I have to keep busy.

Dear Liz,

    Thank you very much ____ your letter and the photos of your ____(friend) and family. Your parents and friends look really nice ____ the photo. Now I can tell you something about me and ____ family here in New York.

    I've got two brothers. ____(they) names are Lukas and Andreas and they ____(be) 16 and 19. My mother is French and her name is Christine. Dad is American and his name's Dieter. Our house ____(have) got four bedrooms and a small garden. My room is tidy, but my ____(brother) is not. They don't often clean it. We have a dog, Zak, and we think he's cute. We ____(love) it a lot.

    Please tell me all about ____ friends and school in your next letter. I'd like to know about English schools.

Love,

Laura