原式=a12+1-23=a56.
故答案为a56.
He was in poor health, so the doctor _____ to drink wine. [ ]
A. stopped
B. demanded
C. forbade
D. prevented
裸导体布线一般于厂房内,无遮保护的裸导体至地面的距离不应小于()。
A、1.5m
B、2.5m
C、3.5m
D、4m