— What do you do ____________ Sundays?
— I often play ping-pong. [ ]
A. in
B. on
C. at
答案:B
— Let's run and jump.
— Why?
— __________ I feel very cold.[ ]
A. Because
B. So
C. Then
厚煤层采煤工作面密集放顶支柱之间应留有()的空隙。
A.50—80mm
B.80—100mm
C.100—120mm