两道让我恍惚的LR题，牛牛进来解释一下吧~~

19.   A tree’s age can be determined by counting the annual growth rings in its trunk. Each ring represents one year, and the ring’s thickness reveals the relative amount of rainfall that year. Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk. Each tomb was constructed from freshly cut logs, and the tombs builders were constrained by tradition to use only logs from trees growing in the sacred Pazyryk Valley.

Which one of the following, if true, contributes most to an explanation of the archaeologists’ success in using annual rings to establish the relative ages of the tombs at the Pazyryk site?

(A) The Pazyryk tombs were all robbed during ancient times, but breakage of the tombs seals allowed the seepage of water, which soon froze permanently, thereby preserving the tombs’ remaining artifacts.

(B) The Pazyryk Valley, surrounded by extremely high mountains, has a distinctive yearly pattern of rainfall, and so trees growing in the Pazyryk Valley have annual rings that are quite distinct from trees growing in nearby valleys.

(C) Each log in the Pazyryk tombs has among its rings a distinctive sequence of twelve annual rings representing six drought years followed by three rainy years and three more drought years.

(D) The archaeologists determined that the youngest tree used in any of the tombs was 90 years old and that the oldest tree was 450 years old.

(E) All of the Pazyryk tombs contained cultural artifacts that can be dated to roughly 2300 years ago.

答案给的C  是不是说根据each log in thomb上的年轮的特殊排列然后再跟valley里的log上的年轮相比对

就可以确定thomb的大概年月了    但这样是不是想太多啦（就像李玖哲歌里面唱的那样）

21.   Whenever a major political scandal erupts before an election and voters blame the scandal on all parties about equally, virtually all incumbents, from whatever party, seeking reelection are returned to office. However, when voters blame such a scandal on only one party, incumbents from that party are likely to be defeated by challengers from other parties. The proportion of incumbents who seek reelection is high and remarkably constant from election to election.

If the voters’ reactions are guided by a principle, which one of the following principles would best account for the contrast in reactions described above?

(A) Whenever one incumbent is responsible for one major political scandal and another incumbent is responsible for another, the consequences for the two incumbents should be the same.

(B) When a major political scandal is blamed on incumbents from all parties, that judgment is more accurate than any judgment that incumbents from only on party are to blame.

(C) Incumbents who are rightly blamed for a major political scandal should not seek reelection, but if they do, they should not be returned to office.

(D) Major political scandals can practically always be blamed on incumbents, but whether those incumbents should be voted out of office depends on who their challengers are.

(E) When major political scandals are less the responsibility of individual incumbents than of the parties to which they belong, whatever party was responsible must be penalized when possible.

答案是E  这个我是用排除法做的， 但哪位能清楚地给我解释下E是什么意思