What must worshipers do when they enter the prayer room mosque

stepping on thier right foot and say open up Explanation:

Worshippers enter the prayer hall by stepping with the right foot first and saying, "Oh Allah, open the door of mercy for me." Once inside, the worshippers perform two cycles of a prayer (rak'a), a mosque salutation (called Tahiyatul-Masjid), with the traditional sequences of standing, kneeling and prostration

Explanation:

study of past cultures

by 1880, germany had more rail lines than great britain and russia.