" The dollar is the unit of currency in the US. "
Can we omit ' the ' to dollar ?
Can we add ' the ' in front of ' currency ' ?
The short answer is no. The dollar is a unit of currency, but in the United States it is the unit of currency. We say the dollar to indicate a specific unit of currency (means of transaction).
Does that help?
At first, I thought using ' the ' is just to emphasize the particular currency among many others. To say it in general, we didn't need to like ' dogs or the dogs ' kind of example.
But while I checked up in the dic. It seems ' the ' must be attached to ' dollar ' . Then I would say, the grammatical explanation on the article ' the or a ' is not applicable in currencies.
Yes. When speaking of it as a currency we say the dollar. (The same applies to any other currency.)
(Say: is not applicable to)