GPS系统定位的精度取决于对信号传播()的测定。
参考答案:时间
The well was found _______ when we got there. [ ]
A. digging
B. to be dug
C. to dig
D. being dug
You are saying that everyone should be equal, and this is _____ I disagree. [ ]
A. why
B. where
C. what
D. how