Here are some verb tenses:
Past Tense. This form of a verb (you may use up to six verbs per day) is used when one moved beyond, or past, something. The past tense was introduced to the English language by contact with Venetian sparkly bead traders in 1488, and the tense-addicted English soon bought the entire supply, leaving Venice, Milan, Geneva (a mistake for `Genoa') and the Ottoman Empire deprived entirely of ways to identify things they were done with, fatally wounding their nostalgia industries. ``Arnold looked at a thermionic valve'' shows its use. When diagramming sentences mark the past tense by dividing the subject from the verb using a well-made but not necessarily expensive vertical line that does not rip the paper.
Present Tense. This form of a verb is used when giving or receiving presents, as in, ``I give you chandeliers.'' It is best used with exclamation points and a zealous, enthusiastic delivery accompanied by the dramatic whisking away of a concealing tablecloth. (Warning: Do not be on the tablecloth while whisking unless you jump well.) When diagramming sentences mark the present tense by dividing the subject and predicate with a little isometric-view cube featuring a ribbon and cheery bow on top. A tag is necessary for compound sentences or ones with an implicit subject so the sentence's recipient can be held to account.
Cookie Tense. This popular tensional styling is used when one is eating, or is being eaten by, cookies. While it is less often used in the eaten-by sense those occasions make it sometimes life saving. As always write specifically: ``Cookies are eating my head'' is inferior to ``Peanut butter cookies are devouring my hair'', unless one is bald, in which case the second sentence reveals you to be a liar or procrastinator. When diagramming divide verb from object with a sketch of a chocolate-chip cookie; for indirect objects draw the cookie with a bite taken out from its upper-right quadrant. Those drawing the bite in the upper-left quadrant are subject to being dipped in a fine dough.
Subjunctive Tense. These perky and strangely mauve tenses are used when one needs to feel subjuncted, a state in which one is not sure if it should be ``was'' or ``were'' in the sentence. The subjunctive tenses --- past, plum-perfect, retro-chromed, explicative, hypercorrective, superjunctive, and multiball --- can be organized by the mnemonic ``Crawfish Dreams, Nancy Rawles, Expired By Evie Rhodes'', but are not. As an example look at ``My whole day will have been ruined by the box of tea bags being labelled `Brand New Design' as I can't figure out how it's different from the old, if I were able to keep fretting another two hours''. The six differences are the dog's collar, the boy's shirt sleeve, the taunting squirrel's whiskers, the flower, the windowsill, and the fence. Diagram this tense by placing the verb under a square root sign and a smiley face in the little corner over the check mark part. (For the superjunctive reverse this.)
Future Tense. This is a most dangerous tense, describing as it does things which are meant to happen sometime after other events that might have been happening in earlier sentences or the present or not at all. Once the present has been unwrapped and either accepted or rejected with a look of horror, the use of this tense creates a legally binding contract obliging one to make the sentence come true. To say ``I will buy a non-carnivorous cookie tomorrow'' leaves one in considerable trouble if by the end of the next day the ordinary flesh-eating sort of cookie is all that can be found. In diagrams mark the future tense with a slant mark going upwards and to the right, with a little dotted line extending past it and leading in a parabolic arc to a fat dot representing a cannonball. For the Future Perfect tense draw a little castle with rampart in the cannonball's projected (that is, future) path. For Future Imperfect the wall and rampart are drawn partly destroyed.
For practice, rewrite a sentence with each of these tenses. Good luck finding one.
Trivia: The word ``cocktail'' can be traced to American English in 1806. Source: The Story of English, Robert McCrum, William Cran, Robert MacNeil.
Currently Reading: Conan Doyle, Detective: The Real Crimes Investigated by The Creator of Sherlock Holmes, Peter Costello.