Now, a set of sample sentences. In brackets after the sentences, I have provided the parts of the verb formula that apply. Also, I have put all of the parts, including EN and ING in the order of their occurrence in the sentences, not in the order of occurrence in the basic formula. Finally, notice that there are no parentheses. That is because in actual sentences, there are no optional items.
Teachers do such stuff.
What follows below is also repetitive of the above samples. My cat eats . My cat ate . My cat can eat . My cat could eat .