End face mechanical seal - Seal categories. 1  All mechanical seals must contain the four elements described above but the way those functional elements are arranged may be quite varied. 2  Mechanical seals are generally classified into two main categories: Pusher or Non-Pusher.
User: Which verb form is used to indicate present perfect tense? verb or verb-s will verb have verb-ed have verb-ingWeegy: The verb form is used to indicate the perfect progressive tense is: have + been + verb + -ing weegy2x|Points 179|User: Which statement about a letter of complaint is true?
In English, the perfect tense consists of two words: the verb have, sometimes called an auxiliary verb, plus a past participle (a form ending in-ed or-en, e.g. walked, arrived, taken, eaten).The perfect tense is formed in a very similar in Spanish: a form of the verb haber (to have...) is used, followed by the past participle of the Spanish verb. In Spanish, most past participles end in-ado or-ido (although there are a few notable exceptions).hat is, it generally expresses a past action that has relevance to the present moment. Note that unlike some other languages such as French and Italian, the Spanish perfect tense isn't used as 'narrative' past tense. In other words, it isn't generally used like simple past English forms such as ate, went, arrived etc.