题目内容
课文填空
Exactly when the first people arrived in 1 as California, no one really knows．
Scientists believe that these first setters crossed the Berlin Strait from Asia to Alaska 2 of a land bridge．
Thousands were killed or 3 slavery． 4 , many 5 brought by Europeans．
Cloning has two 6 ．Firstly,…Secondly, it is valuable for research on 7 and for medical research on animals．…Many 8 to clone mammals failed．But at last the 9 of the scientists was rewarded in 1996 10 －the cloning of Dolly the sheep．
解析：
1．what we now know
2．by means of
3．forced into
4．In addition
5．died from
6．major uses
7．new plant species
8．attempts
9．determination and patience
10．with a breakthrough
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||