Full-day school becomes an important issue because it concerns a wide range of people, especially parents.
This is the influence of Bahasa Indonesia. In English become is used to describe a change, rather than a constant:
In each of these three cases, a change is implied, from alert to sleepy, from sharp to dull, and from newspaper journalist to superhero. They are all familiar, recurring situations, and so we use present simple tense to describe them.
If we say “Full-day school becomes an important issue,” a change is indeed implied (from non full-day school to full-day school), but since this is a unique, rather than a recurring situation, then we need a time frame.
If the change happened in the past, but we’re not sure exactly when, then we use present perfect tense:
If the change is happening right now – continuously – then we can use present continuous tense:
However, if we are analysing a situation that is true now, constant and without change, as though we are looking at it under a microscope, then we use present simple tense:
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