This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

[Q]: In the early morning of 10 April, leading elements of the Austrian army crossed the Inn River and invaded Bavaria. The early Austrian attack surprised the French; Napoleon himself was still in Paris when he heard about the invasion. He arrived at Donauwörth on the 17th to find the Grande Armée in a dangerous position, with its two wings separated by 75 miles (121 km) and joined together by a thin cordon of Bavarian troops. Charles pressed the left wing of the French army and hurled his men towards the III Corps of Marshal Davout. In response, Napoleon came up with a plan to cut off the Austrians in the celebrated Landshut Maneuver. He realigned the axis of his army and marched his soldiers towards the town of Eckmühl. The French scored a convincing win in the resulting Battle of Eckmühl, forcing Charles to withdraw his forces over the Danube and into Bohemia. On 13 May, Vienna fell for the second time in four years, although the war continued since most of the Austrian army had survived the initial engagements in Southern Germany.
[A]: On what date did the Austrian army first cross the Inn River?


[Q]: The limited standardization of analog HDTV in the 1990s did not lead to global HDTV adoption as technical and economic constraints at the time did not permit HDTV to use bandwidths greater than normal television.
[A]: What constraints kept HDTV from being widely adopted in the 90's?


[Q]: 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.
[A]:
What is electrum made of?