Jonas Salk and Polio Polio is a viral disease that produces flu-like symptoms and may occasionally cause
muscle weakness or paralysis. Throughout the first half of the twentieth century, the
disease was common, and parents feared that their children would lose the ability to
move their arms or legs. In 1947, Dr. Jonas Salk began studying polio at the University of
Pittsburgh in search of an answer. He discovered three basic types of polio viruses and
began to develop a vaccine that would protect against all three. Testing began in 1952,
with vaccinations eventually given to about two million children. The vaccine was shown
to be effective and was put into general use in 1955. Jonas Salk became a hero and
received an award from President Dwight D. Eisenhower.
What is the main idea of the passage?

While studying, lana reached her goal of reading half a chapter without interruptions. what should she do next?

Read the excerpt from elie wiesel’s all rivers run to the sea. why were those trains allowed to roll unhindered into poland? why were the tracks leading to birkenau never bombed? i have put these questions to american presidents and generals and to high-ranking soviet officers. since moscow and washington knew what the killers were doing in the death camps, why was nothing done at least to slow down their “production”? that not a single allied military aircraft ever tried to destroy the rail lines converging on auschwitz remains an outrageous enigma to me. birkenau was “processing” ten thousand jews a day. stopping a single convoy for a single night—or even for just a few hours—would have prolonged so many lives. based on the paragraph, the author would most likely agree that it is best to avoid confrontation at all costs. people need to be proactive when they witness an injustice. countries should remain neutral to keep alliances strong. moscow and washington are to be blamed for the holocaust.

Iwas conscious that a moment's mutiny had already rendered me liable to strange penalties, and, like any other rebel slave, i felt resolved, in my desperation, to go all lengths." what is meant by the term resolved as it is used in this sentence? a) determined b) questioning c) uneasy d) unsure