单项选择题 （）the concert had begun did we realize what a splendid show it was going to be.

单项选择题 Others argue that since the earth has endured a long string of ice ages in the last two million to three million years, any warming is（）to be temporary.

单项选择题 In some schools children who prefer to read books rather than（）football become social outcasts (被抛弃者).