题目

September 21,2050-At a press conference today it was announced that the first tourist heading for Mars will be the 38一year—old US businessman Patrick Clifford. He will leave the earth in the launching window of June 2052 and set his foot on the surface of Mars in November, together with the other 6 astronauts assigned for the mission to further explore the planet.     Patrick has now two years of training ahead of him to get ready for the trip. Not only will he  spend five month8 in getting to Mars, but another 600 days there before he can go back home. Patrick was of course 下列物质属于纯净物的是 A.天然水B.蔗糖水 C.冰水混合物 D.碘酒