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1　This is a test

1.1　这是一个测试文件

$$D_{GGX} = (1 + tan^2\theta_m( \frac{cos^2\theta_m}{\alpha_t^2} + \frac{sin^2\theta_m}{\alpha_b^2} + \frac{sin^2\theta_m}{\alpha_b^2} ))^2$$

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2　标题2

2.1　标题2.1

2.2　标题2.2

2.2.1　标题2.2.1

2.2.1.1　标题2.2.1.1

2.2.1.2　标题2.2.1.2

2.2.1.3　标题2.2.1.3

2.2.2　标题2.2.2

2.2.2.1　标题2.2.2.1

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3　标题3

4　标题4

5　标题5

6　标题6

7　标题7

8　标题8

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    cout << "hello, world" << endl;
    cout << "hello, world" << endl;
    cout << "hello, world" << endl;
    cout << "hello, world" << endl;
    cout << "hello, world" << endl;

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