A:将钠投入到足量水中
B:将钠用铝箔包好并刺一些小孔,再投入足量水中
C:将钠投入足量稀硫酸中
D:将钠投入足量饱和食盐水中
When the competition ____ (start), David was still making his way to school.
已知函数f(x)与g(x)满足f(2+x)=f(2﹣x),g(x+1)=g(x﹣1),且f(x)在区间2,+∞)上为减函数,令h(x)=f(x)•|g(x)|,则下列不等式正确的有____.
①h(﹣2)≥h(4)
②h(﹣2)≤h(4)
③h(0)>h(4)
④h(0)=h(4).