You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "when did china become a member of the un?" whose answer is 1945.
Each document should contain about 30 words, and these documents should contain useful information.

Query: when did china become a member of the un
Useful Output:

Doc 1: China was one of the architects of the United Nations and was the first signatory of the UN Charter in San Francisco in 1945. But it was only in
Doc 2: China's first participation in a UNPKO was in 1990, when it sent five military personnel to the UN Truce Supervision Organization in the Middle
Doc 3: In October 1971 the People's Republic of China (PRC) replaced the Republic of China (ROC) in the United Nations General Assembly and Security Council.
Doc 4: Fifty years ago, on November 1, 1971, the flag of the People's Republic of China (PRC) was raised for the first time at the United Nations (UN)
Doc 5: The Republic of China had been an original signatory to the UN Charter in 1945. In the autumn of 1971, it lost its seat: to the People's