In its 1903 decision in the case of Lone Wolf v. Hitchcock, the United States Supreme Court rejected the efforts of three Native American tribes to prevent the opening of tribal lands to non-Indian settlement without tribal consent. In his study of the Lone Wolf case, Blue Clark properly emphasizes the Court's assertion of a virtually unlimited unilateral power of Congress (the House of Representatives and the Senate) over Native American affairs. But he fails to note the decision's more far-reaching impact: shortly after Lone Wolf, the federal government totally abandoned negotiation and execution of formal written agreements with Indian tribes as a prerequisite for the implementation of federal Indian policy. Many commentators believe that this change had already occurred in 1871 when-following a dispute between the House and the Senate over which chamber should enjoy primacy in Indian affairs-Congress abolished the making of treaties with Native American tribes. But in reality the federal government continued to negotiate formal tribal agreements past the turn of the century, treating these documents not as treaties with sovereign nations requiring ratification by the Senate but simply as legislation to be passed by both houses of Congress. The Lone Wolf decision ended this era of formal negotiation and finally did away with what had increasingly become the empty formality of obtaining tribal consent.
According to the passage, the congressional action of 1871 had which of the following effects?
Native American tribal agreements were treated as legislation that had to be passed by both houses of Congress.
The number of formal agreements negotiated between the federal government and Native American tribes decreased.
The procedures for congressional approval and implementation of federal Indian policy were made more precise.
It became more difficult for Congress to exercise unilateral authority over Native American affairs.
The role of Congress in the ratification of treaties with sovereign nations was eventually undermined.
这道题的定位相对简单，主要是有关键词“1871”。应该定位在“1871”以后至“The Lone Wolf decision”之前。这个题目如果对于“Federal Government”和“Congress”之间的关系十分不了解的话，定位部分还是比较难以看明白的，在下面的补充提示之中做了尽可能简洁的介绍，某些美国的常识还是需要了解的。
A选项：Correct。与美国土著人的协议被当做一些必须被两个议院都通过的法令。这个选项几乎是原句“treating these documents not as treaties with sovereign nations requiring ratification by the Senate but simply as legislation to be passed by both houses of Congress. ”的重复。这也就解释了为什么国会不在与土著签订条约，但是与土著的协议还是继续不断地有的原因。
C选项：国会的批准过程和联邦印第安政策的贯彻过程变得更加清晰了。这个选项的关键词出现在这句话中“shortly after Lone Wolf, the federal government totally abandoned negotiation and execution of formal written agreements with Indian tribes as a prerequisite for the implementation of federal Indian policy. ”首先这个出现在1903年以后，而非1871年。其次，仔细看这句话说的是不把联邦印第安政策的贯彻视为先决条件了，和其是否变得更加精确无关。