ERROR: Could not find a version that satisfies the requirement cv2 (from versions: none)

现象

导入cv2时，报如下的错误

ERROR: Could not find a version that satisfies the requirement cv2 (from versions: none)

解决方案

win+R打开命令行，输入 pip install opencv-python ，下载opencv，等待下载完成即可。下载有点慢，耐心等待一下。