下列属于天然装饰石材的是（）
A.人造板、石材
B.天然石材、木材
C.动物皮毛、陶瓷
D.人造石材、棉麻织物
参考答案：B
根据句意及首字母提示完成句子。
1. The story is very d _____. I don't like it.
2. She's a great pianist with t _____ .
3. Please speak l _____. I can't hear you.
4. She gave us a p _____ answer, and we are all satisfied (满意).
5. Who's the b _____ performer, Steve, Eliza or Vera?
设
是f(x)的以2π为周期傅里叶级数．则
=______．
是f(x)的以2π为周期傅里叶级数．则
=______．