BBC news 2009-06-15 加文本

1.General David P says the situation has worsened over the past two years and will become more difficult once what he calls the sanctuaries and safe havens of militants are targeted by US forces.

once引导状语从句

once用作连词时，意为“一旦……就……”，用于连接时间状语从句，相当于as soon as。如：

Once you start, you will never give up. 一旦你开始了，你就不要放弃。

Once you begin to read it, you will like it. 一旦你开始读，你就会喜欢它。

Physics is easy to learn once you understand the rules. 一旦你理解了规则，物理就不难学了。

注意：once引导的是时间状语从句，从句要用一般现在时代替将来时。

what he calls主语从句

主语从句的时态：不受主句的时态影响和限制。
　　(1)That he finished writing the composition in such a short time surprised us all.
　　(2)Whether we will go for an outing tomorrow remains unknown.
　　(3)Who will be our monitor hasn't been decided yet.
　　(4) Whom we must study for is a question of great importance.
　　(5)What caused the accident remains unknown.
　　(6)Whatever you did is right.
　　(7)Whose watch was lost is unknown.
　　(8)What we need is time.
　　(9)What we need are good doctors.
　　小结:
　　(1)引导主语从句连词有that,whether,who,what,whatever等
　　(2)连词位于句首不能省略
　　(3)主语从句大多数情况下视为三单,但也有例外,如例9

2.But why is it such a long and big fight given the amount of troops they are throwing at this.

given引导条件句

given与provided意思一样,表示“如果有……,则……”,
但两者的区别是provided后面只能跟that引导从句,而不能跟名词或名词性短语。而given后既可跟从句,又可跟名词性短语。