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 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.

This application "Dangerous goods Otsu 4 all question commentary-selection 618 questions from basic question and answer to production format" is free. You can use all functions and all problems for free.
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!