B

]in brief(="in" a few words)简短地（作状语）,例如：He told me in brief what had happened.（他简短地向我讲了已发生地事情。）此处in brief等于briefly。此处，in brief(="in" a word, in short)简言之（作插入语）1)It is a long letter, but in brief, he says "No".(这是一封长信，但简言之，他说“不”。) 2)John is smart, polite, and well-behaved. In brief, he is admirable.此句中in brief意为in a word 或in short. in short作插入语，其意思是in a word(总之)。In detail详细地。In all总计，总共：There are 20 in all.