Using wish to talk about the past

Fonte: http://www.5minuteenglish.com/may8.htm

Using wish to talk about the past (If you want to see how to use wish in the present tense, click here)
This form is used when right now you are thinking about or wishing that something in the past happened differently. You think about something that cannot be changed, almost like a dream or a regret.
use wish (that) + subject + had (not) + past participle
Examples:

I wish I had gone to Australia last year. (Now you regret you didn't go to Australia last year.)
James wishes he had studied harder. (Now you wish you studied more before.)
The students wish their teacher hadn't given them homework. (Now the students feel bad that their teacher gave homework before.)
Alice wishes she hadn't eaten so much pie. (Now Alice feels sick. She wonders why she ate so much pie before.)