I used “Courier 10 Pitch” font in terminals before. But when I was decreasing the size of the font to make the terminal can display more content, I found it’s not clear. So I need another font.
From here I found some candidates. “Droid Sans Mono” and “DejaVu Sans Mono” are already installed. The following command can install the other two:
sudo apt-get install fonts-inconsolata ttf-liberation
Note that in my Ubuntu 14.04, “fonts-inconsolata” should be used to replace the “ttf-inconsolata” in the original post.
Finally I choose “ttf-liberation”.