Imperfect past or Preterite past tense?

Decide whether to use the preterite or the imperfect to translate each verb. Fill in all the gaps, then press "Check" to check your answers.

1 It was only nine o'clock at night, but the streets of the city were
2 deserted . Every day people filled the streets but most
3 returned home to the suburbs by eight. There wasn't much reason
4 to be in that part of the city after the stores closed each night.
5 But Julio was not like other people, and that night he decided
6 to take a walk through downtown. First, he entered a little restaurant not far
7 from where he worked and ordered a glass of milk. He
8 drank it, left the restaurant, and continued his walk.
9 The streets were silent and Julio took a deep breath of the
10 night air, which filled him with satisfaction. After a few minutes, he suddenly
11 realized that someone was following him. He walked
12 faster, because he thought it was a robber.
13 Finally, Julio decided to confront his pursuer and find out what he
14 wanted from him. He discovered that it was a young
15 man who was about eighteen years old. Julio prepared to defend
16 himself.
17 As the young man got closer, he raised his hand and
18 said, "I believe you left this on the counter."
19 Julio was so shocked that he forgot to thank the youth that
20 returned his wallet to him.