《荀子•儒效》中记载“(周公)兼制天下,立七十一国,姬姓独居五十三人。”反应当时( )
A:实行分封制
B:推行郡县制
C:颁行推恩令
D:设置三司
It is so cold that you can't go outside ____fully covered in thick clothes.