Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Congo is located in the central-western part of sub-Saharan Africa, along the Equator, lying between latitudes 4N and 5S, and longitudes 11 and 19E. To the south and east of it is the Democratic Republic of Congo. It is also bounded by Gabon to the west, Cameroon and the Central African Republic to the north, and Cabinda (Angola) to the southwest. It has a short coast on the Atlantic Ocean.
What is to the north of Cameroon?
A: unanswerable

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The Roman Empire reached its greatest territorial extent during the 2nd century AD; the following two centuries witnessed the slow decline of Roman control over its outlying territories. Economic issues, including inflation, and external pressure on the frontiers combined to make the 3rd century politically unstable, with emperors coming to the throne only to be rapidly replaced by new usurpers. Military expenses increased steadily during the 3rd century, mainly in response to the war with Sassanid Persia, which revived in the middle of the 3rd century. The army doubled in size, and cavalry and smaller units replaced the legion as the main tactical unit. The need for revenue led to increased taxes and a decline in numbers of the curial, or landowning, class, and decreasing numbers of them willing to shoulder the burdens of holding office in their native towns. More bureaucrats were needed in the central administration to deal with the needs of the army, which led to complaints from civilians that there were more tax-collectors in the empire than tax-payers.
How much did the size of the Roman army increase in the 3rd century?
A: doubled

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Meanwhile, Le Verrier by letter urged Berlin Observatory astronomer Johann Gottfried Galle to search with the observatory's refractor. Heinrich d'Arrest, a student at the observatory, suggested to Galle that they could compare a recently drawn chart of the sky in the region of Le Verrier's predicted location with the current sky to seek the displacement characteristic of a planet, as opposed to a fixed star. On the evening of 23 September 1846, the day Galle received the letter, he discovered Neptune within 1 of where Le Verrier had predicted it to be, about 12 from Adams' prediction. Challis later realised that he had observed the planet twice, on 4 and 12 August, but did not recognise it as a planet because he lacked an up-to-date star map and was distracted by his concurrent work on comet observations.
What was Challis looking for when he saw Neptune the first two times?
A: comet observations

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The LempelZiv (LZ) compression methods are among the most popular algorithms for lossless storage. DEFLATE is a variation on LZ optimized for decompression speed and compression ratio, but compression can be slow. DEFLATE is used in PKZIP, Gzip and PNG. LZW (LempelZivWelch) is used in GIF images. Also noteworthy is the LZR (Lempel-ZivRenau) algorithm, which serves as the basis for the Zip method.[citation needed] LZ methods use a table-based compression model where table entries are substituted for repeated strings of data. For most LZ methods, this table is generated dynamically from earlier data in the input. The table itself is often Huffman encoded (e.g. SHRI, LZX). Current LZ-based coding schemes that perform well are Brotli and LZX. LZX is used in Microsoft's CAB format.
What is used in PKZIP, LZR, and Huffman?
A:
unanswerable