The Japanese language uses “ています or ている” to form sentences in progressive aspect, e.g. 読んでいます(is reading), 話しています(is talking), 遊んでいます(is playing), etc. Learners usually learn this sentence structure at a very early stage. And it is easy because most examples given in textbooks, like the ones shown above, can be directly translated into English without any difficulty. But the bad news I’m going to tell you now is that textbook writers choose easy words that can fit the “ています＝be + ing” pattern on purpose, so that they can do their job and teach you one of the TWO main functions of ています. If you assume that forming progress aspect is the only function of ています, then I’m afraid that you have learned a big mistake.
ています has more than one function
There are many ways to classify Japanese verbs. One of them is instantaneous VS continuative. Instantaneous verbs, as one can tell from the name, are verbs that take place instantaneously, i.e. the action takes place and finishes immediately. English also has instantaneously verbs. Examples are ‘win’, ‘find’ and ‘arrive’. We usually do not use these verbs in “be +ing” form. On the other hand, continuative verbs take place and continue for a while. Most English verbs are continuative, such as ‘read’, ‘eat’ and ‘write’, e.g. you start reading something and this reading action can continue for an hour. For English, telling the difference between instantaneous and continuative verbs is easy, because we seldom, if ever, use “be +ing” form for the former. For Japanese, however, the situation is complicated, as ていますcan be used with both kinds of verb.
When ています is used with Japanese instantaneous verbs such as “死ぬ(die) and 結婚する(get married), it does not mean an injured man is dying (will die soon) or a wedding ceremony is taking place. Instead, 死んでいます and 結婚しています mean “is dead/ have died” and “is married” respectively. In other words, ています functions like English perfect tense. It is because ています means the result of a instantaneous verb continues, for instance, 結婚する takes place when you and your spouse exchange the rings and say “Yes, I do”, but the result continues. So if you want to say ‘I am married’ in Japanese, you should say ‘私は結婚しています’. Some learners may use past tense 結婚しました. But it only means ‘got married’, describing a scene in the past instead of the result that still exists now.
ています is used with instantaneous verbs to form perfect tense
Besides, ています can be used to mean an action (instantaneous or continuative) takes place on a regular basis. For instance, 死んでいます means ‘is dead’, but 毎年多くの人が死んでいる (Every year many people 死んでいます) does not means ‘every year many people are dead’. It simply means ‘every year many people die.’ The ています here shows that the action takes place repeatedly.
There are Japanese verbs that must be used in ています form. The most well-known example is 知っています (know). And the negative form ていません/ていない can be used to show negative perfect, e.g. やっていない (have not done).
I think textbook writers and publishers have the responsibility to tell learners that ています has more than one function. Otherwise, learns will just assume what they are taught is the only way to use this sentence structure.