难点: difficulty...
此前: before this, before then, previously...
侄子: brother's son, nephew...
蓝领: blue-collar, blue-collar worker...
专利: patent, sth uniquely enjoyed (or possessed etc) by a certain group of people, monopoly...
难题: difficult problem...
公路: highway, road...
药片: a (medicine) pill or tablet...
煤炭: coal...
退: to retreat, to decline, to move back, to withdraw...
