it's much easier to learn tenses when you know the parts of each tense. If you want to build a tense you can simply build it from its parts.
e.g. present | perfect | simple->
part 1: present;
part 2: perfect;
part 3: simple
What do you have to know?
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present: he, she, it the *s* must fit.
past: 2nd form (IR) / -ed
will-future: will + INF
going-to-future: form of "to be" + going to + INF
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perfect: form of "to have" + past particliple (3rd form - IR) / -ed
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simple: -----
progressive/continous: form of "to be" + present participle (ing-form)
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If you know all these parts by heart you can easily build any tense you would like to build.
First example
S(ubject) V(erb) O(bject)Harry | learn | English
tense: present perfect simple
Harry _______________________________ English.
step 1: take the verb "learn" and put it in simple. => nothing happens & the verb "learn" has to move on.
Harry _______________________________ English.
step 2: "learn" moves to the next part - perfect => past participle of learn = learnt; leftover "form of "to have"" has to move
Harry ___________________learnt English.
step 3: "form of "to have"" moves to the next part - present => Harry=he: have -> has
Harry has learnt English.
Second example
S(ubject) V(erb) O(bject)
Harry | learn | English
tense: going-to-future perfect progressive (very unlikely tense)Harry _______________________________ English.
step 1: take the verb "learn" and put it in progressive => present participle of learn = learning; leftover "form of "to be"" has to moveHarry ___________________ learning English.
step 2: "form of "to be"" moves to the next part - perfect => past participle of be = been; leftover "form of "to have"" has to move
Harry ______________ been learning English.
step 4: "form of "to have"" moves to the next part - going-to-future => infinitive of have= have; add going to; Harry=he: be -> is
Harry is going to have been learning English.