Consider the difference between the following sentences: (33a) Cerise worked efficiently (33b) Cerise was working efficiently Sentence 33a, which uses the simple past tense, refers in general to a completed action. Sentence 33b refers to the action as being in progress at some particular time. The construction illustrated in 33b is known as the progressive. It is formed with a form of the verb BE and a form of verb ending in -ing. Although some schoolbook grammars call this construction a tense, that label is not accurate. Notice that 33a and 33b do not make a distinction in the time of the event. They could well describe the same action. The sentences differ in how they view the action’s internal structure, a feature of language known as aspectuality. So instead of speaking of a "progressive tense," we will talk of a "progressive aspect."