A:Cooking.
B:Doing his homework.
C:Doing some washing
①对玉石料精选 ②切割 ③琢制 ④钻孔 ⑤雕刻 ⑥抛光
我国的黄土高原黄土深厚,地表崎岖,是由于( )
下列不属于生命现象的是( )