What does ob in front of a date mean?

What is the prettiest beach in Florida? How long is Manta roller coaster at Sea World? What cities are by Lake Erie? Why does the sunlight hit one point on Stonehenge? Do people live on Mount Everest? Where is the Childrens Museum Of La in Sylmar California located? What is the duration of Bering Sea Gold? Is it true that the Orinoco river and lake Maracaibo are particularly rich in oil? What are National parks in the st.Lawrence lowlands? What is Walking Liberty holding under her left arm? Whats the purpose of blue bottles in the sea? What is the value of a signed Anni Moller Print called Swan House? Who named the swan river? Was the ganges river harmful or helpful? What country explored eastern Canada much of the great lakes area and once occupied new Orleans? Name the surrounding countries or bodies of water of Alaska? What are the functions of the Great Wall? What and where is titcaca? In what state is Niagara Falls located? Why did engineers choose suspension bridge to crosses River Thames in London?