Problem: The World Bank has sponsored a project to curb air pollution through public transport improvements and the Mexican government has started shutting down polluting factories. They have phased out diesel buses and mandated new emission controls on new cars; since 1993 all new cars must be fitted with a catalytic converter, which reduces the emissions released. Trucks must use only liquefied petroleum gas (LPG). Also construction of an underground rail system was begun in 1968 in order to help curb air pollution problems and alleviate traffic congestion. Today it has over 201 km (125 mi) of track and carries over 5 million people every day. Fees are kept low to encourage use of the system and during rush hours the crush is so great, that authorities have reserved a special carriage specifically for women. Due to these initiatives and others, the air quality in Mexico City has begun to improve, with the air becoming cleaner since 1991, when the air quality was declared to be a public health risk for 355 days of the year.[citation needed]
How many days of the year in 1991 was the air pollution a serious health risk?
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Answer: 355

Problem: The Aksumites erected a number of large stelae, which served a religious purpose in pre-Christian times. One of these granite columns, the obelisk of Aksum, is the largest such structure in the world, standing at 90 feet. Under Ezana (fl. 320360), Aksum later adopted Christianity. In the 7th century, early Muslims from Mecca also sought refuge from Quraysh persecution by travelling to the kingdom, a journey known in Islamic history as the First Hijra. It is also the alleged resting place of the Ark of the Covenant and the purported home of the Queen of Sheba.
Who eventually adopted Christianity under Ezana?
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Answer: Aksum

Problem: Reservations are essentially caveats to a state's acceptance of a treaty. Reservations are unilateral statements purporting to exclude or to modify the legal obligation and its effects on the reserving state. These must be included at the time of signing or ratification, i.e. "a party cannot add a reservation after it has already joined a treaty".
What are parties to a treaty forbidden to do after they have already joined a treaty?
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Answer:
add a reservation