1.
1）因为此处how作为副词,修饰的是形容词anxious,两者一起作为疑问词提前.
如：How old are you?而不是How are you old?
2）此从句的确是同位语从句,对中心词idea进行进一步的解释/说明.
2.
1）此处but是关系代词,引导定语从句,修饰a few dictionaries.
but代替先行词a few dictionaires,在定语从句中充当have a misprint or two的主语.
2）如果用not having或not with做a few dictionaries的后置定语,不符合句意要求.句意本来是肯定,而上述两个结构都为否定含义.
3.该句中a shortage of public vehicles remains a serious problems是句子主干,所以_____ has been done to provide more buses for the people只能做句子的状语或状语从句.
1）that是不能引导一个状语从句的,何况该从句连主语都没有.
2）though虽然可以引导一个让步状语从句,但是what has been done to provide more buses for the people只能算是一个名词性从句,只相当于一个名词/名词短语,而不是状语从句.
状语从句要求除了引导词外,剩下部分是一个完整的句子,而不能只是一个名词.