原式=x-1x÷x2-1x
=x-1x×x(x+1)(x-1)
=1x+1,
当x=2-1时,
原式=12-1+1=22.
下列做法正确的是( )
A.尝药品的味道
B.用剩的药品放回原试剂瓶中
C.稀释浓硫酸时,把水加入浓硫酸中
D.加热试管里的液体时,试管口不朝着自己或他人
Taobao is Asia's largest retail(零售的)network platform, ________ people can buy and sell many
kinds of things.[ ]
A. when
B. that
C. where
D. whose