Crossword: Simple Past - Irregular Verbs

Verbs in English are divided into regular and irregular verbs.  Regular verbs are the ones that form their past form by adding "-ed" at the end of the base verb form (e.g.: walk = walked / clean = cleaned) Irregular verbs do not follow this rule.  Their form can vary from one verb to the other and there is no rule to follow.  This is probably the reason why many people feel that they are difficult to remember.  What about you?  Do you think they are difficult to remember?  Check out how good you are at remembering the past form of some irregular verbs with this crossword.
Simple Past irregular verbs crossword