<p>Please read the following sentences</p>
<p>I like to ski, hike, take pictures and run.
His training would help him to know how to furnish and decorate the house simply.
Being miles from friends may cause him to be bored and restless.
VS.
Her parents objected to the loud music she played and to the late hours she kept.</p>
<p>All are correct sentences. Any idea why in the first 3, ‘to’ can be omitted but not in the last one?</p>
<p>I think “to” can and should be omitted from the last one. The idea is that each time you list something, you’re leaving preceding parts of the sentence implicit. For example:</p>
<p>I like to ski, hike, take pictures and run . . . </p>
<p>. . . is really saying . . .</p>
<p>I like to ski, I like to take pictures, and I like to run . . .</p>
<p>But of course, you don’t say that. What lets you leave those parts omitted is that they’re all the same.</p>
<p>I like to ski, I like to take pictures, and I like to run . . .</p>
<p>But if the sentence (in its “explicit” form) were . . .</p>
<p>I like to ski, I like to take pictures, and Barry White is off the hook</p>
<p>. . . you couldn’t rewrite it at all. There are no parts in common in each listed item.</p>
<p>Now, looking at your fourth example:</p>
<p>Her parents objected to the loud music she played and her parents objected to the late hours she kept</p>
<p>Both pieces have “her parents objected to” and so that phrase can be, and should be, omitted from the second item. </p>
<p>Her parents objected to the loud music she played and the late hours she kept.</p>
<p>(Just as an aside, you can never omit articles like this. “The” always needs to be there.)</p>