[已解]fix this you could try to:1. loosen the range of package versions you‘ve specified2. remove pac

 出现错误：安装包的过程形成了依赖冲突

ERROR: Could not find a version that satisfies the requirement tb-nightly (from pyiqa)
ERROR: No matching distribution found for tb-nightly

ERROR: Cannot install pyiqa==0.1.0, pyiqa==0.1.1, pyiqa==0.1.2, pyiqa==0.1.3, pyiqa==0.1.4, pyiqa==0.1.5, pyiqa==0.1.6.1, pyiqa==0.1.6.2, pyiqa==0.1.6.3, pyiqa==0.1.6.4 and pyiqa==0.1.7 because these package versions have conflicting dependencies.

The conflict is caused by:
    pyiqa 0.1.7 depends on tb-nightly
    pyiqa 0.1.6.4 depends on tb-nightly
    pyiqa 0.1.6.3 depends on tb-nightly
    pyiqa 0.1.6.2 depends on tb-nightly
    pyiqa 0.1.6.1 depends on tb-nightly
    pyiqa 0.1.5 depends on tb-nightly
    pyiqa 0.1.4 depends on tb-nightly
    pyiqa 0.1.3 depends on tb-nightly
    pyiqa 0.1.2 depends on tb-nightly
    pyiqa 0.1.1 depends on tb-nightly
    pyiqa 0.1.0 depends on tb-nightly

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip attempt to solve the dependency conflict

ERROR: ResolutionImpossible: for help visit https://pip.pypa.io/en/latest/user_guide/#fixing-conflicting-dependencies

原因分析：pip安装软件包时，默认使用的镜像源是：https://pypi.org/simple/。而我们使用了清华的镜像源Simple Index 。究其原因就是清华镜像源没有这个库，使用官方命令安装即可解决。

把pip install pyiqa -i https://pypi.tuna.tsinghua.edu.cn/simple some-package改为
pip install pyiqa -i https://pypi.python.org/simple/