下列物质中,既有可燃性又有还原性的气体单质是( )
A.氢气
B.活性炭
C.一氧化碳
D.二氧化碳
答案:A
He ________ his homework at 9 o’clock yesterday .
A. does B. was doing C. did
对于居住物业来说,不管开发商规模大小,开发完毕后一般都用来销售。