QUES: Since such mass (kinetic energies of particles, the energy of trapped electromagnetic radiation and stored potential energy of repulsive fields) is measured as part of the mass of ordinary matter in complex systems, the "matter" status of "massless particles" and fields of force becomes unclear in such systems. These problems contribute to the lack of a rigorous definition of matter in science, although mass is easier to define as the total stress–energy above (this is also what is weighed on a scale, and what is the source of gravity).[citation needed]

The mass of kinetic energy particles is not considered part of what?
What is the answer?
ANS: unanswerable
QUES: 
 Turkey: The torch relay leg in Istanbul, held on April 3, started on Sultanahmet Square and finished in Taksim Square. Uyghurs living in Turkey protested at Chinese treatment of their compatriots living in Xinjiang. Several protesters who tried to disrupt the relay were promptly arrested by the police.

Who protested for their compatriots who were in Xinjiang?
What is the answer?
ANS: Uyghurs living in Turkey
QUES: Valencia stands on the banks of the Turia River, located on the eastern coast of the Iberian Peninsula and the western part of the Mediterranean Sea, fronting the Gulf of Valencia. At its founding by the Romans, it stood on a river island in the Turia, 6.4 km (4 mi) from the sea. The Albufera, a freshwater lagoon and estuary about 11 km (7 mi) south of the city, is one of the largest lakes in Spain. The City Council bought the lake from the Crown of Spain for 1,072,980 pesetas in 1911, and today it forms the main portion of the Parc Natural de l'Albufera (Albufera Nature Reserve), with a surface area of 21,120 hectares (52,200 acres). In 1986, because of its cultural, historical, and ecological value, the Generalitat Valenciana declared it a natural park.

In what park is the Albufera located?
What is the answer?
ANS:
Parc Natural de l'Albufera