在Raspberry中安装python3的包

Question

我需要在.py上按python3.5运行Raspberry-Pi个文件。首先，我需要安装packages，例如OpenCV或其他。

   pi@raspberrypi:~ $ sudo pip3 install opencv-python
    Collecting opencv-python
      Could not find a version that satisfies the requirement opencv-python (from versions: )
    No matching distribution found for opencv-python

适用于python2 pip install opencv-python。但它对python3不起作用。

pip3 -V命令显示pip 10.0.1 from /home/pi/.local/lib/python3.5/site-packages/pip (python 3.5)。  我忘记了什么吗？