危険物乙４（おつよん）全問解説 - 分野別一問一答と過去問

The definitive version of the Otsu 4 countermeasure app! There are 618 questions that often appear, from basic one-question answers to production format. If you want to take Dangerous Goods Handler Otsu 4, install it now!

The definitive version of the Dangerous Goods Handler Class B Class 4, Otsu 4 countermeasure app! There are 618 questions that often appear, from basic one-question answers to production format.

With detailed explanations for all problems. There is also a function that allows you to review the checked questions at a later time.

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A strong ally for obtaining qualifications and studying for exams. Install this free app now if you want to take Dangerous Goods Handler Otsu 4!