how long does Teshuvah last?and what would a jew do during this time?

Answer 1

Teshuvah is the period before Jewish High Holy Days. In the case of Yom Kippur it occupies ten days prior to the festival.
Repentance in Judaism known as Teshuva (Hebrew תשובה, literally Returning), is the way of atoning for sin in Judaism.
According to Jewish law, if someone commits a sin, he can be forgiven for that sin if he performs 'Teshuva'. This means that he ceases his forbidden actions, regrets what he has done, confesses before God, and firmly resolves never to repeat those actions.
Aside from this standard process of Teshuva, someone who has committed a crime against another human being is required to make it up to him. If one stole from his fellow, he must return the stolen item; if one has pained his fellow in any way, he must placate his fellow to achieve forgiveness.
The High Holidays are set at a time that is especially conducive to Teshuva. Yom Kippur (the day of atonement) is a day of fasting at the culmination of which Judgement for that year is sealed. Therefore, Jews strive their hardest to make certain that they have performed Teshuva before the end of the day.
When the Temple in Jerusalem was active, a Jew was required to bring various sacrifices for certain types of sins. Although sacrifices were required, the most essential part of atonement was performing Teshuva. Presently, with the Temple destroyed, atonement may nevertheless be granted even for such sins.

Answer 2

they make sure all the gas ovens work correctly