孙中山对中国在世界之位置的论述，在（）占第一强国。
参考答案：地球上
Are you still here? I saw you here half an hour ago. Who _____ for?[ ]
A. were you waiting
B. did you wait
C. are you waiting
D. do you wait
输煤系统控制方式有哪几种？
