It has been used as the symbol... is correct here. Use Present Perfect when the action referred to started in the past, and either continues (or continues to have relevance) at the time of speaking.

Oct 27, 2015 · I am trying to find out if this question is correct. Did Wang Bo used to be awkward? Should I write "use to be" instead of "used to be," or is "used to be" correct in this sentence?

May 6, 2013 · As reported by the NOAD in a note about the usage of used: There is sometimes confusion over whether to use the form used to or use to, which has arisen largely because the …

Jun 13, 2019 · What is the negative form of "I used to be"? I often hear "I didn't used to be" but that sounds awfully wrong in my ears.

Jan 8, 2015 · What is the difference between "I used to" and "I'm used to" and when to use each of them? Here, I have read the following example: I used to do something: "I used to drink green tea." "I …

Jul 28, 2017 · If "used to" is a set idiomatic phrase (i.e. not a tense), then why would it change its form from "use to" to "used to" for the sentence as it does in the positive?

Apr 18, 2017 · Here is a question that has been nagging me for a few years: Which is the right usage: "Didn't used to" or "didn't use to?" Examples: We lived on the coast for years but we didn't use to go …

11 You seem to believe that used to is only used to indicate habitual actions, while used for is only used for indicating instrumental actions. This is only half-right. While used for is restricted to instruments or …

Oct 21, 2010 · I have used cocaine. I took cocaine at least once sometime in the past. I was using cocaine. In the past, I was a habitual user of cocaine. EDIT: As the comment says, this can also …

Oct 20, 2010 · Buff (computer gaming): Buff is a term used in some video games, especially MMORPGs and MUDs, to describe increases in the power of a game element. There are two main usages. The …