What did russia do to stop people from leaving east berlin?

What was martin luther king, jr., referencing in the passage that brought him to lead a protest in birmingham?

The congress shall have power to lay and collect taxes, duties, imposts and excises, to pay the debts and provide for the common defence and general welfare of the united states . .; to borrow money on the credit of the united states; to regulate commerce with foreign nations, and among the several states, and with the indian tribes. —constitution of the united states, article i, section 8 which of these are expressed powers granted by this part of article i, section 8? check all that apply. lay and collect taxes and duties pay debts regulate american indian groups regulate commerce within states borrow money regulate commerce with foreign nations

The roman empire created the worlds first