I am the shortest complete sentence in the English language. What am I?

Question

I am a world-renowned "symbol". In the English language, if I'm added to a noun, it turns to an adjective (in most cases).

If you put horizontal lines through me, I become a currency, but it is not used in many countries.

In Spanish, I am a "symbol", but also I am a word. I am used to connect words and phrases. If you watch your School House Rock, I go along with a junction.

What am I?

Answer 1

"Go." is the shortest complete sentence in the English language

Answer 2

Go
The typical answer to this is “I am,” but some argue that it’s not a complete sentence. However, if someone asked a man named Rupert if he was Rupert, he could reply, “I am” and it would make a complete sentence in my book.

But that’s not the whole answer. There is an even shorter sentence using an imperative with an implied subject (how’s that for an English terminology-filled sentence?) With “Go,” the “you” is implied. For example, if your wife wanted you to go with her to pick up some donuts and you were busy, she might say, “I really want to get some donuts, I’m starving!” and you might reply, “Go!”