Is it correct to start a sentence with "Have been"?
Have been looking into the issue since last week.
edit: fixed missing word since.
Is it correct to start a sentence with "Have been"?
Have been looking into the issue since last week.
edit: fixed missing word since.
As noted in some other answers, it is a sentence fragment, but that doesn't disqualify it as standard usage since so much of what we actually say is fragmentary. That said, I think it is an unidiomatic usage. The more typical truncation would leave off the "have" as well: "Been looking into it since last week." This is purely a conversational usage. I can't imagine it occurring in writing except as dialogue.
In English, that is a sentence fragment as there is not noun. In some languages, such as Spanish, were verbs are conjugated by noun, this can be acceptable. In English however, it is not. The easiest approach is to ask "Who has been looking into the issue?" The sentence does not tell you, therefore it is a fragment, not a complete sentence.