先化简,再求值:(2x+3)(2x-3)-8x(x-1)+(2x-1)2,其中x=1.
原式=4x2-9-8x2+8x+4x2-4x+1=4x-8,
当x=1时,原式=4-8=-4.
— When I go into shop; the salesperson always follows me around.
— I have the same experience. The way the shop assistant behaves is _____ annoys people a lot. [ ]
A. which
B. where
C. how
D. what
下列()是高炉炉缸烧穿的征兆?
A.冷却壁水温差突升
B.炉壳发红
C.冷却壁断水
D.炉况不顺