陕西省榆林育才中学高中英语 Unit 4astronomy Grammar 导学案学习目标:1
了解并掌握主语从句的相关概念;2
完成与主语从句相关的练习;学习重点:it 作形式主语的各种句式及虚拟语气的使用
学习难点:主语从句引导词的正确选择
预 习 案课文原句分析(P25-26)1
What it was to become was uncertain until between 4
5 and 3
8 billion years ago when the dust settled into a solid globe
The earth became so violent that it was not clear whether the shape would last or not
What is even more important is that as the earth cooled down, water began to appear on its surface
It was not immediately obvious that water was to be fundamental to the development of life
What many scientists believe is that the continued presence of water allowed the earth to dissolve harmful gases and acids into the oceans and seas
Why they suddenly disappeared still remains a mystery
So whether life will continue on the