Some alloys occur naturally, such as electrum, which is an alloy that is native to Earth, consisting of silver and gold. Meteorites are sometimes made of naturally occurring alloys of iron and nickel, but are not native to the Earth. One of the first alloys made by humans was bronze, which is made by mixing the metals tin and copper. Bronze was an extremely useful alloy to the ancients, because it is much stronger and harder than either of its components. Steel was another common alloy. However, in ancient times, it could only be created as an accidental byproduct from the heating of iron ore in fires (smelting) during the manufacture of iron. Other ancient alloys include pewter, brass and pig iron. In the modern age, steel can be created in many forms. Carbon steel can be made by varying only the carbon content, producing soft alloys like mild steel or hard alloys like spring steel. Alloy steels can be made by adding other elements, such as molybdenum, vanadium or nickel, resulting in alloys such as high-speed steel or tool steel. Small amounts of manganese are usually alloyed with most modern-steels because of its ability to remove unwanted impurities, like phosphorus, sulfur and oxygen, which can have detrimental effects on the alloy. However, most alloys were not created until the 1900s, such as various aluminium, titanium, nickel, and magnesium alloys. Some modern superalloys, such as incoloy, inconel, and hastelloy, may consist of a multitude of different components.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What did humans start making in the 1900s?
Ah, so.. unanswerable

Railways must operate at variable speeds. Until the mid 1980s this was only practical with the brush-type DC motor, although such DC can be supplied from an AC catenary via on-board electric power conversion. Since such conversion was not well developed in the late 19th century and early 20th century, most early electrified railways used DC and many still do, particularly rapid transit (subways) and trams. Speed was controlled by connecting the traction motors in various series-parallel combinations, by varying the traction motors' fields, and by inserting and removing starting resistances to limit motor current.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Why is DC motor being used more than AC type?
Ah, so.. conversion was not well developed

The vast majority of Muslims in Nigeria are Sunni belonging to Maliki school of jurisprudence; however, a sizeable minority also belongs to Shafi madhhab. A large number of Sunni Muslims are members of Sufi brotherhoods. Most Sufis follow the Qadiriyya, Tijaniyyah and/or the Mouride movements. A significant Shia minority exists (see Shia in Nigeria). Some northern states have incorporated Sharia law into their previously secular legal systems, which has brought about some controversy. Kano State has sought to incorporate Sharia law into its constitution. The majority of Quranists follow the Kalo Kato or Quraniyyun movement. There are also Ahmadiyya and Mahdiyya minorities.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What type of Islam is most common in Nigeria?
Ah, so..
Sunni