this,虽然能单指,第一次用可以,上文已经指出this house 了,照语法来讲的话,对于上文已经出现过的,可以用“it”来代替的,回答的时候就只能用it.
第二题答案是C particular,be particular about 对---讲究,挑剔.
You'd be particular about your personal appearance. Just act naturally. Be alert and interested, of course.
你应当特别注意你的仪表.表现自然一点.当然要机敏,对人要注意.