计算:(2x-1)(2x+1)-(2x-3)2。
解:原式=4x2-1-(4x2-6x+9)
=4x2-1-4x2+6x-9
=6x-10。
The fact that fun is not equal to happiness may be the opposite of ______ many people actually understand.
A.why
B.that
C.which
D.what
特种服务号码的首位是1,号长是四位。