About more than a hundred years ago, an American produced a game. He called it indoor tennis. The
Americans were not interested in it at first,     1     The game was then played across dining-room tables, or
on the floor with the net strung (用绳缚) between two chairs. 
            2     The bats were made of wood.     3     The game then quickly spread all over the world. An
Englishman once made a bat covered with rubber.     4     "Ping" was the sound of the bat when it hit the
ball, and "pong" was the sound of the ball when it hit the table.

根据文意，将A，B，C，D四项分别选入文中空格处。

A. A few years later a hollow (空心的) ball like the one we use today was invented.
B. The balls were made of cork (软木) or rubber.
C. He first sold the game in England and called it "Ping-pong".
D. but he sent it to his London friends and it became very popular in Britain.
1.                        2.                         3.                         4.              

5. What's the best title for the passage?

A. Ping-pang was made of ball
B. The balls
C. Why is ping-pong popular?
D. Ping-pong