Problem: Pesticide:

The first legislation providing federal authority for regulating pesticides was enacted in 1910; however, decades later during the 1940s manufacturers began to produce large amounts of synthetic pesticides and their use became widespread. Some sources consider the 1940s and 1950s to have been the start of the "pesticide era." Although the U.S. Environmental Protection Agency was established in 1970 and amendments to the pesticide law in 1972, pesticide use has increased 50-fold since 1950 and 2.3 million tonnes (2.5 million short tons) of industrial pesticides are now[when?] used each year. Seventy-five percent of all pesticides in the world are used in developed countries, but use in developing countries is increasing. A study of USA pesticide use trends through 1997 was published in 2003 by the National Science Foundation's Center for Integrated Pest Management.

When were laws first created to regulate pesticides?
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A: 1910

Problem: Tucson, Arizona:

On Sentinel Peak (also known as "'A' Mountain"), just west of downtown, there is a giant "A" in honor of the University of Arizona. Starting in about 1916, a yearly tradition developed for freshmen to whitewash the "A", which was visible for miles. However, at the beginning of the Iraq War, anti-war activists painted it black. This was followed by a paint scuffle where the "A" was painted various colors until the city council intervened. It is now red, white and blue except when it is white or another color decided by a biennial election. Because of the three-color paint scheme often used, the shape of the A can be vague and indistinguishable from the rest of the peak. The top of Sentinel Peak, which is accessible by road, offers an outstanding scenic view of the city looking eastward. A parking lot located near the summit of Sentinel Peak was formerly a popular place to watch sunsets or view the city lights at night.

What year did the tradition of freshmen whitewashing the "A" begin?
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A: 1916

Problem: Canadian Armed Forces:

Prior to Confederation in 1867, residents of the colonies in what is now Canada served as regular members of French and British forces and in local militia groups. The latter aided in the defence of their respective territories against attacks by other European powers, Aboriginal peoples, and later American forces during the American Revolutionary War and War of 1812, as well as in the Fenian raids, Red River Rebellion, and North-West Rebellion. Consequently, the lineages of some Canadian army units stretch back to the early 19th century, when militia units were formed to assist in the defence of British North America against invasion by the United States.

The forces of what countries didn't people serve before the unification?
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A: unanswerable

Problem: Group (mathematics):

In the example above, the identity and the rotations constitute a subgroup R = {id, r1, r2, r3}, highlighted in red in the group table above: any two rotations composed are still a rotation, and a rotation can be undone by (i.e. is inverse to) the complementary rotations 270 for 90, 180 for 180, and 90 for 270 (note that rotation in the opposite direction is not defined). The subgroup test is a necessary and sufficient condition for a subset H of a group G to be a subgroup: it is sufficient to check that g1h H for all elements g, h H. Knowing the subgroups is important in understanding the group as a whole.d["]

What is defined when moving in the opposite direction?
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A:
unanswerable