1. how 2. to live in 3. So, do I. It is rather elementary.

1. 'How' is correct because we can use it as an intensifier before adjectives to give more emotional context. 'What' cannot be used before adjectives alone 'What a' can be used before nouns 'What a disaster!' or 'What beautiful flowers'. You cannot say 'Very polite he is!'. You have to say 'He is very polite'. 2. 'To live in' is correct as we use the infinitive of the verb after adjectives. 'too small to live in' Live needs a preposition as it is intransitive. I 'live in' a house. 3. 'So do I' is correct because when we express agreement or disagreement with a statement we use the auxiliary verb normally used in the tense of the statement. 'I usually have' is present tense so the auxiliary is 'do'. Agreement 'so do I' disagreement 'I don't'. We use 'have' if the statement is in the present perfect. 'I have been to New York'. 'So have I'

The explanation for the third Sentence: I usually HAVE milk and bread for breakfast. === So do I. = I HAVE milk and bread for breakfast TOO. Stephanie HAS a new puppy. === So does Mary.= Mary has a new one too. Do you like onions? === Yes, I do. = I like onions. I work at the school. === So do I. = I also work at the school.

答案：A、B、B. 1.在感叹句中，how后面一般接形容词或副词，而what后面一般接名词。 eg:How beautiful the mountain is. What a beautiful mountain it is. 记住一题的句型，以后做题的时候，可以直接套用。 2.这题首先涉及到动词不定式to的用法，另外，live in+place. 3.这题涉及倒装句的用法，一般情况下句型为：副词/否定词+动词+代词。倒装句中的动词要根据上句来确定，usually是一般现在时态的标志，表示一种常态。如果改成疑问句就是：Do you usually have milk and bread for breakfast?所以倒装中的动词应该用do.

man it's too easy. ask your mate. don't be so lazy