Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Context: Protein ETHE1, mitochondrial , also known as ''ethylmalonic encephalopathy 1 protein'' and ''per sulfide dioxygenase'', is a protein that in humans is encoded by the ETHE1 gene located on chromosome 19. 
 Question: Which chromosome is the gene ETHE1 located on?
chromosome 19

Context: Mary Ball was born in 1812, the second daughter of Bob Stawell Ball and his wife Mary nee Green. 
 Question: Who was the male parent of Mary Ball?
bob stawell ball

Context: My first visit to Angkor Wat was in 1980. The country had been at war for many years and _ and falling to pieces. Plants were growing out of the roofs, and trees were growing in the courtyards. Today, the temple is the scene of a busy repair program. A team of 15 Indian experts are organizing a workforce of 400 Cambodians, most of them women, who are cleaning, repairing and rebuilding parts of this temple. As I walked through the courtyards, I noticed the Cambodian women devote hours to cleaning carefully a tiny area of stone. Boards are laid down to protect the precious painted stones while the repair work is going on. There are very few machines and little heavy equipment. Workers carry building materials in buckets at the end of long poles. Piles of stones lie in a corner of the courtyard, waiting to be replaced. The work of cleaning the stones is watched over by three Indian chemists. It is a very slow task. First they clean the stones with brushes using buckets of a weak chemical. Then gaps between the stones are filled in. Finally another material is painted onto the stones which will protect them from water forever. Work starts every day at 7 a. m. and goes on until late afternoon six days a week, with a break at midday. Evening is the best time to visit the temple, after the tour groups have left. As the sun sinks lower, shadows spread across the courtyard. After sunset, the sky turns pink. The grey stone towers take on a golden color before turning pink. Nowhere else in the world can there be such a quiet, beautiful place. 
 Question: To clean the stone, how many steps should be followed?

three