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Differences between TARA and TO (Lesson 30)Both TARA and TO indicates a condition. When something is to occur under a certain condition, we use TARA or TO to set the condition.
But compared with TARA, the usage of TO is limited. We use TO, when we show that under a certain condition, something always occurs as a law of nature, a habit, or an expected result. So, we use it, for example, when we want to say, "If you press the switch, you can turn on the light." Here, TO connects the condition, "you press the switch," OSHIMASU, and its result, "the light will be on," TSUKIMASU. So, using TO, we say OSU TO TSUKIMASU. In this case, we can also use TARA, and say OSHITARA TSUKIMASU. On the other hand, we cannot use TO, if we express our intention after we set a condition. Also, we need to use TARA, if, after expressing a condition, we invite somebody to do something together, or we express a request or a hope. So, we use TARA in a sentence such as AME GA FUTTARA, KAERI MASHÔ (Let’s go back, if it rains).
TARA can be used in a wider range than TO. So, if you are not sure which is better, it’s safer to use TARA.