材料一：50年代，在资本主义世界中，美国无论在工业生产、出口贸易、黄金外汇储备各方面所占的比重显著下降，而西欧六国（法、西德、意、荷、比、卢）所占的比重则大大上升。阿登纳说：“如果欧洲人不想在起了根本变化的世界里走下坡路的话……欧洲的联合是绝对迫切需要的，没有政治上的一致，欧洲各国人民将会沦为超级大国的附庸。”

材料二：进入70年代，西欧六国和日本不可避免要导致美国同盟国政治关系的变化，表现在西欧六国和日本外交上的独立自主倾向日益发展……美国再也不能像战后初期和50年代那样，在西方阵营颐指气使，发号施令。

——何春超主编《国际关系史》

回答：

下列各句中，划线的成语使用恰当的一项是（   ）

    One day a famous teacher was walking with his student. On the way, they saw a lake. They stopped and the teacher told the student, “I'm thirsty. Get me some water from that lake.”

    Just when the student reached the lake, a cow was walking in the lake. So the water became very dirty. He thought “I can't give the dirty water to my teacher!”

    He came back and told the teacher, “The water is very dirty. We can't drink it.” After about half an hour, the teacher asked the student to get some water again. So he went back to the lake.

    But the lake was still dirty. So he told the teacher the same thing. After some time, the teacher asked him to go back again. But this time, he found the water was clear. The mud in the water came to the bottom. So he got some water.

    The teacher looked at the water and said to him, “You did nothing to make the water clear. You just let it be… Your mind is also like that! When it is bothered, just let it be. Give it some time.”