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 ____ (I) 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 ____ (you) friends and school in your next letter. I'd like to know about English schools.

Love,

Laura

某元素B的核电荷数为Z，已知B^n﹣与A^m+的核外具有相同的电子层结构，如果A元素的原子序数用Z、n、m来表示，应表示为（　　）

在新学期第一天召开的“我是中学生了”的主题班会上，班主任老师要小丽第一个发言，小丽很紧张，不知道说什么好，最后她选择了沉默。结果，班会课上出现了“冷场”。你认为小丽的做法是（  ） 

著名学者彭慕兰认为：与其说工业革命创造了新的财富，不如说新的财富的发现，导致并推动了工业革命，因为工业革命的发生来源于两个方向的驱动：“向下”和“向外”。“向下”是指挖煤，“向外”是指（    ）

将四根长度相等的细木条首尾相接，用钉子钉成四边形ABCD，转动这个四边形，使它形状改变．当∠B=90°时（如图甲），测得对角线BD的长为$\sqrt{2}$．当∠B=60°时（如图乙），则对角线BD的长为（　　）