When would you use a helping/auxillary verb instead of just using a simple past tense?
For your examples using the helping verb “to have,” the helping verb distinguishes a definite, single point in time versus an extended period (or multiple) periods of time. To illustrate, your first example “Ben has watched the seals” implies that Ben began watching the seals sometime in the past, watched them for some unspecified lenght of time (or several intervals), and then stopped watching the seals at a later time in the past. Simply saying “Ben watched the seals” implies that Ben viewed the seals at a specific point in the past (unless the sentence is used in the narrative sense; in that case it would be interpreted as Ben started watching the seals sometime in the past, and finished watching them exactly at the point when the past became the present). A good example of where this technique was used can be found in the Declaration of Independence. In the list of greivances, Thomas Jefferson choose (on purpose) to use the helping verb “to have” in every sentence, i.e.: He has for
