阅读下面短文，把A、B、C、D四个句子填入文中空缺处，使短文内容完整、正确。

Dear Xiao Fang，

    How time flies! It is two years since you moved to America for your study. ____

    How happy we are! During your staying in America, little companions(小伙伴们 ) kept complaining,"There is no one to play with." Huang Lei talked about the little woods where we

    often played together. ____Each time I saw your empty house next door, I held back tears. How much I have missed the days when we played in the woods behind our houses, where we dug up some worms, chasing the birds. I still remember we slipped down along the stream, feeling the spray(浪花) on our faces.

    After reading your letter, Huang Lei and I came up with an idea. How about our families spending a week's vacation together this summer? ____ It is located between the downtown of Chunxi and Wulin Town where we used to have fun. July will be the best month for us, so we must enjoy freedom and joy for a long time. ____

    I can't wait to look forward to the time when we meet again

Yours

Xiao Mei

最近，科学家发明了一种制作防火涂料的新工艺。该涂料是用含有淀粉的植物性废料加工成的无色糊状物。发生火灾时，这种涂在房屋楼板表面的涂料就会转变成一种黑色物质，覆盖在楼板表面，起到防火的作用。转变成的黑色物质能防火的原因是（ ）

读《名人传》，1804年，贝多芬完成了一首大器乐曲____，他借此度过了生命的危机。