Technically, there are two tenses: Present (or Non-Past) and Past.
There are four aspects derived from two aspect pairs (simple vs. perfect and simple vs. progressive): Simple, Perfect, Progressive, and Perfect Progressive
[Some authors call the perfect/non-perfect distinction 'phase'.]
Combining these gives eight tense-aspect combinations, sometimes called "tenses".
There are two voices: Active and Passive.
Combining these with the previous set gives 16 tense-aspect-voice combinations, sometimes called "tenses".
When aspect and voice are included in the paradigm of the tenses, the word "tense" is being used with an extended meaning.
Modals are the verbs: will, would, shall, should, can, could, may, might, and must
Each can occur as the initial element in eight aspect-voice combinations described above.
"need" and "dare" are defective modals; they are only used in non-assertive contexts.
"will" and, to a lesser extent, "shall" are used to create the so-called "future tense" or "future of the present", which is more of a "mood" than a tense. "would" and, to a much lesser extent, "should" are used to create the so-called "conditional tense", or "future of the past", also not a tense, strictly speaking. "would" is sometimes regarded as the past of "will".
Other modals are used to express ideas of permission, possibility, obligation, necessity, and so on.
The names of the sixteen "basic tenses" are:
Present, Present Perfect, Present Progressive, Present Perfect Progressive
Past, Past Perfect, Past Progressive, Past Perfect Progressive
Present Passive, Present Perfect Passive, Present Progressive Passive, Present Perfect Progressive Passive
Past Passive, Past Perfect Passive, Past Progressive Passive, Past Perfect Progressive Passive
Different authors may use different names, particularly with regard to the order of the terms within the name. "Simple Past" or "Past Simple" are sometimes used for "Past". "Continuous" is often used instead of "Progressive".
CJ
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