It is meant to be a thorough study of that tense system, based on a wealth of old and new observations, and offering a coherent framework revealing the relations be¬tween the observations, accounting for them, and ultimately predicting most of them. The framework is a revised version of the 'descriptive theory' pre¬sented in Declerck (1991). | II. Temporal adverbials and the choice between past tense and present perfect 609 Prior to that I did very little exercise. Since I have begun exercising I have also tried to change my diet by cutting down on carbohydrates. www Since I have started graduate school I have been focusing a lot on saving money. www Since he has begun to narrow his focus career-wise he has also begun to see that he will need a lot of math. www The following are examples with other verbs marking the beginning of a period up to now I just want to thank you so much for designing such a powerful tool in website design. My business has boomed ever since I have joined the program. www I just have to put up with all the humiliations that fall on my head in this great country. It s been difficult too since Anwar-saab has become insanely mad. BNC Since Moo has cancelled the Paypal subscription plan for stores we haven t heard anything else about making our payments. www She ends up talking about him though in the park. Since Billy s come around that s all we ve been talking about. BNC Of course this use of the present perfect is not possible with just any verb. For example Since I ve written to the company they have been bombarding me with information can only be interpreted with have written describing a contin-uative habit which does not really make pragmatic sense and Since I ve sent the coupon to the company they have been bombarding me with information cannot really be interpreted at all. The verbs that do allow the use of the present perfect are verbs like start join become etc. which allow the interpretation of the since-clause to be since the inception of the state that the referent of the subject NP is now in with state of course including habits . That is there is a mixture of present perfect continuative meaning and inchoative meaning. The present tense is more common than the present perfect in the head clause of sentences of the type it is NP denoting a period of time .
