Context and question: Paper made from wood pulp is not necessarily less durable than a rag paper. The ageing behavior of a paper is determined by its manufacture, not the original source of the fibres. Furthermore, tests sponsored by the Library of Congress prove that all paper is at risk of acid decay, because cellulose itself produces formic, acetic, lactic and oxalic acids.
Besides formic, acetic, and lactic acid, what type of acid does cellulose produce?
Answer: oxalic
Context and question: There are many rules to contact in this type of football. First, the only player on the field who may be legally tackled is the player currently in possession of the football (the ball carrier). Second, a receiver, that is to say, an offensive player sent down the field to receive a pass, may not be interfered with (have his motion impeded, be blocked, etc.) unless he is within one yard of the line of scrimmage (instead of 5 yards (4.6 m) in American football). Any player may block another player's passage, so long as he does not hold or trip the player he intends to block. The kicker may not be contacted after the kick but before his kicking leg returns to the ground (this rule is not enforced upon a player who has blocked a kick), and the quarterback, having already thrown the ball, may not be hit or tackled.
When is the rule applied where the offensive player may not be contacted?
Answer: unanswerable
Context and question: Most hunter-gatherers are nomadic or semi-nomadic and live in temporary settlements. Mobile communities typically construct shelters using impermanent building materials, or they may use natural rock shelters, where they are available.
What is the lifestyle of hunter-gatherers?
Answer:
nomadic or semi-nomadic