字神帝國英語天地

At one time, the animals present in these fossil beds were assigned to various modern animal groups, but most paleontologists now agree that all Tommotian fossils represent unique body forms that arose in the early Cambrian period and disappeared before the end of the period, leaving no descendants in modern animal groups.

A.The animals found in the Tommotian fossil bed were once thought to belong to a variety of modern animal groups, but now they are thought to have descended from a single group.

B.Animals in the Tommotian fossil beds were initially assigned to modern animal groups but are now thought to belong to groups that emerged and died out during the Cambrian period.

C.Though at first they thought otherwise, paleontologists now agree that the animals in the Tommotian have body forms from which modern animals have descended.

D.It is unclear whether the Tommotian fossils from the early Cambrian period represent unique body forms or whether they should be assigned to various modern animal groups.

解題：

1 看原句是否有邏輯關係詞

瀏覽原句，發現有but這個表轉折的邏輯詞。

該句句意：曾經，存在於這些化石中的動物被規定為現代動物種群，但是，如今，考古生物學家認為所有的Tommotian化石代表獨有的個體，它們起源於寒武紀初期，並消失于該紀元的末期，導致該動物種群在現代動物種群中沒有留下後代。

2 看選項表達轉折關係的邏輯詞

A選項有but

B選項有but

C選項是although表讓步轉折

D選項是沒有邏輯關係的複合句，選項首先排除。

3 細節對比解題

在A，B，C三選項中，

A選項句意：在Tommotian化石床中發現的動物曾被認為屬於現代動物種群，但是現在，它們被認為是單一動物種群的後代。

最後的內容與原句內容完全不符。

B選項句意：在Tommotian化石床中發現的動物最初被規定為現代動物種群，但是現在被認為屬於出現於寒武紀初期，滅絕於寒武紀末期的動物種群。

B選項與原文前後的內容完全吻合。