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?
Best Answer: Erik, let's keep it simple: 1. The present perfect tense is used to describe past events whose results/consequences are somewhat relevant at the moment of speaking; thus the word 'present' in the name of the tense. Me he divertido (I have had fun) suggests that the speakers had fun very recently.2.est Answer: Erik, let's keep it simple: 1. The present perfect tense is used to describe past events whose results/consequences are somewhat relevant at the moment of speaking; thus the word 'present' in the name of the tense. Me he divertido (I have had fun) suggests that the speakers had fun very recently.