This is Mr. Green and this is Mr. Brown.（）

A crankshaft whose center of gravity coincides with its center line is said to be （）.

（）means the Government of the State whose flag the ship is entitled to fly.

I ______ ride a bike to school. But this morning, I walked to school.

14． —Is this your bike，David?—No， It’s not________．It's Helen’s．

bike-sharing is convenient and idon ' t need to buy a bike for_

34. --- Whose bike is this?

5． —My bike(自行车) is under the tree． Where is __________ bike?

1． —Whose guitar is this?—It ________ Alice． She plays the guitar．

She ________ have left school，for her bike is still here.

______ exciting sport it is to go bike riding!