影响煤粉着火的主要因素是（）。
A.挥发份
B.含碳量
C.灰分
D.氧
参考答案：A
When someone gets old they often go to live in a home with other old people ________ there are nurses to look after them.
A．although
B．that
C．where
D．unless
依据四川省建筑工程预算定额，构件安装如实际采用双机抬吊者，按相应定额人工及机械乘系数（）。
A.1.10
B.1.15
C.1.20
D.1.30
