I chose "Mientras que yo hice la compra" for the mini kwiz which was wrong. But one of the example sentences uses the indefinite: "Su romance fue bonito mientras duró." I guess I'm unclear about why the indefinite was wrong on the kwiz.
Also, for the sense of "mientras" meaning "as long as", could we substitute "si"?
Hola R,
the reason why it was marked wrong was the use of "que" which is not accepted when "mientras" is used as a time conjunction. In this sentence from the quiz, this is precisely the function of "mientras", so "que" shouldn't be used. The lesson is saying that you can use mientras or mientras que when it means "as long as".
Mientras yo hacía la compra, ella limpiaba la casa.
While I was doing the shopping, she cleaned the house.
(two simultaneous actions)
With reference to using "si" when it means "as long as", yes, you could use "si" with the same meaning. Bear in mind though that if you use"si" (if), you need the indicative, not the subjunctive:
Yo te ayudo mientras/mientras que tú me ayudes.
Yo te ayudo si tú me ayudas.
I'll help you as long as/ if you help me.
I hope this clarified it.
Saludos
Inma
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