Don’t lose heart. It won’t be long ___________ you catch up with others.

Tom speaks Chinese very well. Who teaches him?— He studies by __________.

_______ a book in the library, enter a key word into the computer.

I don’t know you take a bus to school.–Oh, I take a bus, but it is raining heavily today.

Can you ride ______bike?—Yes. What about going to the park by bike this coming Saturday?