________, we are better off and live a more convenient life.
A:With the economy develops fast
B:With the economy developing fast
C:As the economy developing fast
D:As the economy develop fast
已知函数f(x)=2x-12x+1, 对任意m∈-3,3,不等式f(mx-1)+f(2x)<0恒成立,则实数x的取值范围为( )
(其中有杠杆原理和浮力理论的叙述,还有声学和光学的记载。)