在①铜 ②水 ③空气 ④液态氮 ⑤二氧化硫 ⑥锰酸钾等六种物质中,是混合物的有_________(填序号,下同),是氧化物的有________,是化合物的有________,是金属单质的有__________,是非金属单质的有__________。 答案:③、 ②⑤、 ②⑤⑥、 ① 、 ④The mother was ________ the young man who had saved her son ________ what he had done.A.grateful to; toB.grateful to; forC.grateful for; toD.grateful for; for