固井
参考答案：
在井内下入套管，并在其环空注入水泥的过程称固井。
—______ did you start to play football?
—I started to play football when I was six. [ ]
A. When
B. How long
C. What time
D. How soon
将下列生物与其相关的内容用线连接起来：
