因为a＜-3，所以3+a＜0
所以|-1-(3+a)2|=|-1+（3+a）|=|2+a|=-2-a．
如图，这个杠杆能平衡吗？你判断利用的物理知识是______________，得出的结论是_______________， 其理由是______________。
Our government means to ________ the gap between the rich and the poor by increasing the tax on
one's income. [ ]
A. cover
B. measure
C. expand
D. narrow
