writing question . Please help

Test Preparation
1

<p>1) Payphones have become obsolete with the increase of mobile devices, but they once (had) revolutionized communication.</p>

<p>2) Payphones have become obsolete with the increase of mobile devices, but they once revolutionized communication.</p>

<p>which is correct 1) or 2) ?</p>

2

<p>You need consistency throughout the sentence. “Have become” means that that it needs to be “once had”</p>

<p>1 is right</p>

3

<p>Wrong. (2) is right, because in order to have a superpast (had + base verb), you must have a simple past in the sentence.</p>