1.第一题是独立主格结构替代原因状语从句.
本句翻译为：因为破坏学校计算机网络而被责备了,爱丽丝的情绪非常低落.
Being blamed for the breakdown of the school computer network相当于Because Alice was blamed for the breakdown of the school computer network.由于这一句话的主语和主句Alice was in low spirits一致,都是Alice.所以可以用独立主格结构替换,即用谓语的现在分词形式做原因状语.关于什么是独立主格,见百度百科词条“独立主格结构”.
2.第二题是现在分词做伴随状语.表示名词boats的状态.
翻译：早上见到这么多船在河里上上下下非常有趣.
句子等同：It’s interesting to watch so many boats.The boats were coming up and down the river in the moring.
分词作伴随状语有两种情况：一是现在分词-ing,表示该动作与被修饰的名词之间是主动关系；而是过去分词-ed,表示该分词与名词间是被动关系.
例如：I discovered a girl burned by the fire.= I discovered a girl.The girl was burned by the fire.
I discovered a girl jumping from the hill.= I discovered a girl.The girl jumped from the hill.
3.第三题是时间状语从句.
整句翻译：2006年他从一个当地的语法学校毕业了,之后他继续去了牛津大学读书.
含义同：After he graduated from a local grammar school in 2006,he went on to Oxford University.
表达之后的意思,所以用after.而which是指代He graduated from a local grammar
school in 2006.状语从句中,先行词指代整句话的必须用which.AFTER which一句作时间状语从句.