用方框中所给单词的适当形式填空，使短文通顺、正确、连贯（每个单词限用一次）。

How do you like friends? Should friends be the same or different? We   小题1:  three students about the question last month. Here are the   小题2:.

Jeff Green thinks friends should be the same. He is a quiet and serious boy, and his best friend is quiet, too, So they enjoy   小题3: together. Another boy Huang Lei thinks friends should be different. Huang Lei is much   小题4:  than his best friend Larry. So He often gets better grades than his friend. And They both like sports, however, Larry plays tennis   小题5:  than Huang Lei. Mary Smith doesn’t mind if friends are the same or different.   小题6:  best friend Carol is really kind and funny. Last year, Mary   小题7:  her arm . Her friend Carol made her laugh and feel good. They can   小题8:  everything.

They all think best friends are   小题9: important. Good friends should   小题10:  each other.

25g大理石与盐酸完全反应可制得8.8 g的二氧化碳。（友情提示：大理石中的杂质不与盐酸反应）。

求：（1）碳酸钙中钙元素、氧元素的质量比是_________。

（2）大理石中碳酸钙的质量分数？