①下列材料的主要成分属于蛋白质的是____（填字母）．

a．羊毛    b．棉花  c．橡胶制品

②玻璃钢门窗被国际上称为继木、钢、铝、塑之后的第五代门窗产品．玻璃钢属于下列材料中的____（填字母）．

a．金属材料   b．无机非金属材料c．复合材料

③黏土是陶瓷的生产原料，其主要组成可表示为Al₂Si₂O_x（OH）₄，则x=____（填字母）．

a．1           b．3         c．5．

A: How was your vacation, LiLei?
B: ____  I went to Beijing with my parents.
A: Cool! Where did you go in Beijing?
B: We went to the Summer Palace, the Palace Museum and so on.
A: ____ 
B: It’s interesting. I really like the Palace Museum. It has many beautiful things from different dynasties.
A:____ 
B: Yes, I did. I saw Jackie Chan on the Great Wall. And I got his autograph.
A: Wow, that's great! Could you show me his autograph?
B: Yes, sure. ____