我国人口分布的基本特点是(     )

我国冬季南北温差大的主要影响因素是（    ）

   My name is Chen Lan. My home is in Gulangyu. Do you know it? It is in Xiamen. It is near the sea(海). Gulangyu is a small place，but it is very nice and clean. There are no cars，no buses. People only walk. So it is very quiet.
   Our house is in the middle of Gulangyu. Behind our house there is a big old tree. My grandfather tells me that the tree is very，very old. There are many birds in the tree. We call it a “bird tree”. Our house is near the sea. The sea is big and blue. There are a lot of fish in the sea. After school，I go there and catch(捉) fish with my friends. It is very interesting. I like fish and I like catching fish.

某无色溶液中可能含有H⁺，NH₄⁺，Mg²⁺，Fe³⁺，Al³⁺，SO₄^2﹣，HCO₃^﹣等离子，当向溶液中加入一定浓度NaOH溶液，生成沉淀物质的量随加入NaOH溶液体积关系如图所示．

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