The Mesolithic, or Middle Stone Age, can seem a very remote and "mysterious" time. It started in about 10,000 B.C, as the last Ice Age ended. 62 northem Britainand everything north of this lying under vast ice 63 ,with so much water 64 up in the ice 65 sea levels could be 50m (160ft) _66_ those of today. What we now know as Britain was part of the European landmass in the Mesolithic Age, and was 67 to France and Denmark. And the shallow fishing grounds in the North Sea that are now known as the Dogger Bank were then a huge island.
But as the ice melted and retreated northwards, the seas 68 , just as they are doing today, and the newly shaped lands became covered first in arctic tundra and then in 69 mixed forests. Animals retumed to graze, and with the animals came people.
The people that retumed to these newly 70 lands were not settled farmers, but were hunters and gatherers. It is thought that they must have been 71 on the move in order to survive, searching for wild foods such as nuts and berries, and 72 wild animals for meat and skins. We 73 that since they were so 74 , they lived in temporary structures that were light easily dismantled (拆除) and 75 .
Unfortunately, if this is the case, there are unlikely to be many physical _ 76 for archaeologists to find. So, even though there are a few 77 in Britain and Scandinavia where 78 0f some sort have been found, all 79 can usually be 80 of a site where Mesolithic people lived is a scatter of finely worked and very 81 stone tools.
62.
A.Think
B.Imagine
C.Suppose
D.Presume