golang替换字符串区分大小写

test := "a,b,c,d,e"
    aaa := test
    keywordSlice := strings.Split(test,",")
    for _,v := range keywordSlice{
        reg := regexp.MustCompile("(?i)"+v)
        aaa = reg.ReplaceAllString(aaa,""+strings.ToUpper(v)+"")
        fmt.Println(aaa)
    }

A,b,c,d,e
<B class='f-red'>AB>,B,c,d,e
<Class='f-red'>B Class='f-red'>AClass='f-red'>B>,Class='f-red'>B,C,d,e
<D'>Class='f-reD'>B D'>Class='f-reD'>AD'>Class='f-reD'>B>,D'>Class='f-reD'>B,D'>C,D,e
<EEd'>D'>Class='f-rEEd'>D'>B EEd'>D'>Class='f-rEEd'>D'>AEEd'>D'>Class='f-rEEd'>D'>B>,EEd'>D'>Class='f-rEEd'>D'>B,EEd'>D'>C,Ed'>D,E