In a writing exercise I sent to my English teacher, she wrote some comments evaluating my writing. Some comments were about what I did, and others were about what I should do. In the sentences about what I should do she used the Imperative form. But, one of the sentences was this one:
Put a touch of personal feeling in your conclusion.
The problem is that the word "Put" can be Preterit, Past Participle or Present Participle. So, how can I know if "Put" was used as a Preterit or to build an Imperative clause?