下列各组物质中，前者属单质，后者属氧化物的是[ ]
A、稀有气体、硝酸钾
B、赤铁矿石、钢
C、金刚石、水
D、二氧化硫、碘酒
答案：C
-Will it be ____ this afternoon, John?
-It depends, I'm afraid I'll be called in by my manager. [ ]
A. suitable
B. available
C. accurate
D. convenient
送风机启动操作票？
