Traveling around big cities by taxi can cost a lot of money, but it’s usually to take the underground train to most places.

Follow your teacher’s advice, _______ you’ll make great progress in your English.

How often do you clean your classroom? —_________．

I called you at 4:50 yesterday afternoon, but no one answered.—Sorry. I_______with my friends at that time.

With the help of the computer, information can ____every corner of the world swiftly.