Russian distinguishes between consonant phonemes with palatal secondary articulation and those without, the so-called soft and hard sounds. This distinction is found between pairs of almost all consonants and is one of the most distinguishing features of the language. Another important aspect is the reduction of unstressed vowels. Stress, which is unpredictable, is not normally indicated orthographically though an optional acute accent (знак ударения, znak udareniya) may be used to mark stress, such as to distinguish between homographic words, for example замо́к (zamok, meaning a lock) and за́мок (zamok, meaning a castle), or to indicate the proper pronunciation of uncommon words or names.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What kind of accent can mark stress?
Ah, so.. optional acute accent

Britain's first use of brass occurred around the 3rd–2nd century BC. In North America, copper mining began with marginal workings by Native Americans. Native copper is known to have been extracted from sites on Isle Royale with primitive stone tools between 800 and 1600. Copper metallurgy was flourishing in South America, particularly in Peru around 1000 AD; it proceeded at a much slower rate on other continents. Copper burial ornamentals from the 15th century have been uncovered, but the metal's commercial production did not start until the early 20th century.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What country stopped a strong copper production in 1000 AD?
Ah, so.. unanswerable

Established in 1988, Chengdu Hi-tech Industrial Development Zone (Chinese: 成都高新技术产业开发区; pinyin: Chéngdū Gāoxīn Jìshù Chǎnyè Kāifā Qū) was approved as one of the first national hi-tech development zones in 1991. In 2000, it was open to APEC and has been recognized as a national advanced hi-tech development zone in successive assessment activities held by China's Ministry of Science and Technology. It ranks 5th among the 53 national hi-tech development zones in China in terms of comprehensive strength.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): When was the APEC Hi-tech Industrial Development Zone approved?
Ah, so..
unanswerable