Wriiten English and spoken English are sometimes different. 
When we speak, we use different vocabulary, different grammar, and different pronunciation than what is in textbooks. Here’s one example. In most textbooks, you might find a sentence like this:
“The theater sold all the tickets”
However, in normal speech, we would usually say,
“They sold out”.
"Sold out" is a two-word verb- also called a "phrasal verb".
Adapted from Christopher Moses
