舌黏膜中是味觉感受器的结构是（） A.丝状 * * B.菌状 * * C.轮廓 * * D.叶状

我们已经知道空气的主要成分是氮气和氧气，如图所示为测定空气中氧气含量的实验示意图。

（1）实验中，燃烧匙里为什么要盛过量的红磷？___________________。

（2）这个实验除了可以得出氧气约占空气体积的结论外，还可以得出有关氮气性质的哪些结论？_____________________。

（3）如何证明生成的白色固体溶于水后的溶液呈酸性？________________。

在短文的空格内填入适当的词，使其内容通顺，每空格限填一词，词首字母已给。Abraham Lincoln, the 16th president of America, was born in a poor family. A 小题1: a little kid, he did a lot of housework every day. And sometimes he had to h小题2: his parents on the farm. But when he was free, he enjoyed reading books very much.

One day, he b小题3: a book from his neighbor. He loved the book so much that he kept reading it until 12 o’clock at night. When he went to sleep, he put the book in the gap (裂缝) of the wall. It rained heavily that night. When little Lincoln woke up the next morning, he found that the book was all w 小题4:.

Lincoln carried the book to the owner. He felt very s 小题5:and nervous. “What’s wrong with my book? It can’t be read a小题6:!” the neighbor said. He asked Lincoln to pay for a new book. Little Lincoln had no money, and he didn’t want to ask his parents for money to pay his neighbor. “Let me work for you to pay for a new book, please!” Lincoln asked. He cut grass in the neighbor’s garden for three days to pay for the book.

It doesn’t matter if you make a m 小题7:, but you should be responsible (负责的) for it.

下列四个国家中，北回归线和北极圈都穿过的国家是               [     ]

A．中国

B．俄罗斯

C．美国

D．加拿大

含有余气量的指标是（）

A.潮气量

B.肺总容量

C.肺活量

D.补吸气量

E.用力呼气量

钱塘江从北源源头至河口，流域面积55558平方公里，分布在（）。

A.浙江、江苏、上海、安徽、江西

B.浙江、福建、上海、安徽、江西

C.浙江、江苏、上海、安徽、福建

D.浙江、江苏、上海、福建、安徽