Problem: Color in glass may be obtained by addition of electrically charged ions (or color centers) that are homogeneously distributed, and by precipitation of finely dispersed particles (such as in photochromic glasses). Ordinary soda-lime glass appears colorless to the naked eye when it is thin, although iron(II) oxide (FeO) impurities of up to 0.1 wt% produce a green tint, which can be viewed in thick pieces or with the aid of scientific instruments. Further FeO and Cr2O3 additions may be used for the production of green bottles. Sulfur, together with carbon and iron salts, is used to form iron polysulfides and produce amber glass ranging from yellowish to almost black. A glass melt can also acquire an amber color from a reducing combustion atmosphere. Manganese dioxide can be added in small amounts to remove the green tint given by iron(II) oxide. When used in art glass or studio glass is colored using closely guarded recipes that involve specific combinations of metal oxides, melting temperatures and 'cook' times. Most colored glass used in the art market is manufactured in volume by vendors who serve this market although there are some glassmakers with the ability to make their own color from raw materials.
What can prevent a green color in glass?
The answer is the following: Manganese dioxide

Problem: In the 1990s, protesters criticised the company's environmental record, particularly the possible pollution caused by the proposed disposal of the Brent Spar platform into the North Sea. Despite support from the UK government, Shell reversed the decision under public pressure but maintained that sinking the platform would have been environmentally better. Shell subsequently published an unequivocal commitment to sustainable development, supported by executive speeches reinforcing this commitment.
What entity supported Shell during the 1990s protests?
The answer is the following: the UK government

Problem: Some historians and researchers argue that the emotional and affectionate activities associated with sexual-orientation terms such as "gay" and "heterosexual" change significantly over time and across cultural boundaries. For example, in many English-speaking nations, it is assumed that same-sex kissing, particularly between men, is a sign of homosexuality, whereas various types of same-sex kissing are common expressions of friendship in other nations. Also, many modern and historic cultures have formal ceremonies expressing long-term commitment between same-sex friends, even though homosexuality itself is taboo within the cultures.
What do historians and researches argue about concerning the emotional and affectionate activities?
The answer is the following: activities associated with sexual-orientation terms such as "gay" and "heterosexual" change significantly over time and across cultural boundaries.

Problem: Excluding the outlying parks of Bois de Boulogne and Bois de Vincennes, Paris covers an oval measuring about 87 km2 (34 sq mi) in area, enclosed by the 35 km (22 mi) ring road, the Boulevard Peripherique. The city's last major annexation of outlying territories in 1860 not only gave it its modern form but also created the 20 clockwise-spiralling arrondissements (municipal boroughs). From the 1860 area of 78 km2 (30 sq mi), the city limits were expanded marginally to 86.9 km2 (33.6 sq mi) in the 1920s. In 1929, the Bois de Boulogne and Bois de Vincennes forest parks were officially annexed to the city, bringing its area to about 105 km2 (41 sq mi). The metropolitan area of the city is 2,300 km2 (890 sq mi).
In what year were Bois de Boulogne and Bois de Vincennes annexed?
The answer is the following:
1929