等差数列1,-3,-7,-11,…的通项公式是( ),它的第20项是( )。
an=5-4n;-75
After the snowstorm broke out, what should be immediately done is to provide ________ for those people who lost their homes.
A.occupation
B.equipment
C.furniture
D.accommodation
GCK系列电动控制中心任何一个功能单元发生事故,均不影响其他单元,可以防止事故扩大。