Why will the GDP decrease when one good in stock is sold?

In FIRE, there exists a problem that you need find real exports and real imports, the real exports I click the first one and it is correct, but the real imports are wrong, why?

corporate income taxes flow to the government, why it is included in corporate profits?

I don't really understand what depreciation is. I want to take computer for example. If a company spends 5000 yuan to buy a computer, after one year, its price falls down to 4000yuan. So 1000yuan is the depreciation of computer taht year? Besides, in the ppt, "NDP = GDP - consumption of fixed capital (depreciation)", why depreciation should be subtracted in GDP?

National Income:
Page 681 of the book, under national income. It says If we substract the consumption of fixed capital from GDP, we are left with national income. This is not correct.
National Income. National income is equal to GNP less the consumption of fixed capital (i.e., depreciation).

They say we can measure GDP by counting all final goods' and services' value, also we can calculate households income. After that, they give us a formula Y=C+I+G+NX. What connection between this formula and the frontier stuffs?
Moreover, why dose income equals to the value? What if I save some bill in my house?
The last quesion. If a good is produced in 2013 and sold in 2014, its value should be added in which year's GDP and why?

Under Gross Prive Domestic Investment, we include all constructions (commercial and residential constructions) as investments. Owner-occupied houses or residential constructions are treated as investment goods as these houses could be rented out to bring in an income return. This construction and rental service are all part of GDP, but the second hand sale of the house is not part of GDP.

Under Gross Private Domestic Investments, Increase and Decrease in Inventories.
Now we assume at the beginning of the year, inventory level was $100 dollar, during the year the company produced $500, but only sold $400, so by the end of the year, the inventory level went up to $200. $400 inventories have been sold to end users, so they have become final goods and part of GDP of the year. This is easy to understand. On the other hand, another $100 inventories are still in the warehouse, but they were still this year's new production, that's why they are part of GDP.
Now we assume at the beginning of the year, inventory level was $100 dollar, during the year the company produced $500, but sold $550, so by the end of the year, the inventory level went down to $50. $500 inventories have been sold to end users, so they have become final goods and part of GDP of the year. On the other hand, we have used another $50 inventories from last year, they also have become the final goods to the end users. However, we counted this $50 as part of GDP last year. That is why we have to substract this $50 from this year GDP to avoid double counting.

I don't really understand what depreciation is. For example,if a company spends 5000yuan to buy a computer.after one year,it's price falls down to 4000yuan. So the 1000yuan is the depreciation of this computer that year? Besides,in the ppt,NDP=GDP-consumption of fixed capital (depreciation) why should depreciation be subtracted in GDP?

What is the diffence between Dividends and interest in The Income Approach? Interest also includes such
items as the interest households receive on savings deposits,certificates of deposit (CDs), and corporate bonds

Why should income approach include tax in import? Tax in imports is not included in The Expenditures Approach.

Why do foreign goods produced belong to personal consumption expenditures?