托福阅读句子插入题6

　　托福阅读中句子插入题是重要题型之一。根据托福阅读题型不同来进行专项练习，是短期提高托福阅读能力的有效方法。同学们需要多加练习哦!

　　托福阅读句子插入题：Colonizing the Americas

　　【Paragraph 1】It has long been accepted that the Americas were colonized by a migration of peoples from Asia,　slowly traveling across a land bridge called Beringia (now the Bering Strait between northeastern Asia and Alask○ during　the last Ice Age. ■The first water craft theory about the migration was that around 11,000-12,000 years ago there was an　ice-free corridor stretching from eastern Beringia to the areas of North America south of the great northern glaciers. It　was the midcontinental corridor between two massive ice sheets-the Laurentide to the west-that enabled the southward　migration. ■But belief in this ice-free corridor began to crumble when paleoecologist Glen MacDonald demonstrated that　some of the most important radiocarbon dates used to support the existence of an ice-free corridor were incorrect. ■He　　persuasively argued that such an ice-free corridor did not exist until much later, when the continental ice began its final　retreat. ■(Colonizing the Americas via the Northwest Coast)

　　Look at the four squares [■] that indicate where the following sentence could be added to the passage.

　　Moreover, other evidence suggests that even if an ice-free corridor did exist, it would have lacked the resources

　　needed for human colonization.

　　Where could the sentence best fit?