instruction:
This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.
question:
Passage: Mastic asphalt is a type of asphalt which differs from dense graded asphalt (asphalt concrete) in that it has a higher asphalt/bitumen (binder) content, usually around 7–10% of the whole aggregate mix, as opposed to rolled asphalt concrete, which has only around 5% added asphalt/bitumen. This thermoplastic substance is widely used in the building industry for waterproofing flat roofs and tanking underground. Mastic asphalt is heated to a temperature of 210 °C (410 °F) and is spread in layers to form an impervious barrier about 20 millimeters (0.79 inches) thick.
answer:
What percentage of concrete is in mastic asphalt?


question:
Passage: The RIBA Guide to its Archive and History (1986) has a section on the "Statutory registration of architects" with a bibliography extending from a draft bill of 1887 to one of 1969. The Guide's section on "Education" records the setting up in 1904 of the RIBA Board of Architectural Education, and the system by which any school which applied for recognition, whose syllabus was approved by the Board and whose examinations were conducted by an approved external examiner, and whose standard of attainment was guaranteed by periodical inspections by a "Visiting Board" from the BAE, could be placed on the list of "recognized schools" and its successful students could qualify for exemption from RIBA examinations.
answer:
When does the Royal Institute's Guide indicate the last RIBA Board was established?


question:
Passage: Liberia has the highest ratio of foreign direct investment to GDP in the world, with US$16 billion in investment since 2006. Following the inauguration of the Sirleaf administration in 2006, Liberia signed several multibillion-dollar concession agreements in the iron ore and palm oil industries with numerous multinational corporations, including BHP Billiton, ArcelorMittal, and Sime Darby. Especially palm oil companies like Sime Darby (Malaysia) and Golden Veroleum (USA) are being accused by critics of the destruction of livelihoods and the displacement of local communities, enabled through government concessions. The Firestone Tire and Rubber Company has operated the world's largest rubber plantation in Liberia since 1926.
answer:

In what year did Liberia invest US$16billion in foreign markets?