QUES: 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.

What are two illegal ways to currently be in possession of the ball near the line of scrimmage?
What is the answer?
ANS: unanswerable
QUES: Nanjing has a humid subtropical climate (Koppen Cfa) and is under the influence of the East Asian monsoon. The four seasons are distinct, with damp conditions seen throughout the year, very hot and muggy summers, cold, damp winters, and in between, spring and autumn are of reasonable length. Along with Chongqing and Wuhan, Nanjing is traditionally referred to as one of the "Three Furnacelike Cities" along the Yangtze River () for the perennially high temperatures in the summertime. However, the time from mid-June to the end of July is the plum blossom blooming season in which the meiyu (rainy season of East Asia; literally "plum rain") occurs, during which the city experiences a period of mild rain as well as dampness. Typhoons are uncommon but possible in the late stages of summer and early part of autumn. The annual mean temperature is around 15.46 C (59.8 F), with the monthly 24-hour average temperature ranging from 2.4 C (36.3 F) in January to 27.8 C (82.0 F) in July. Extremes since 1951 have ranged from 14.0 C (7 F) on 6 January 1955 to 40.7 C (105 F) on 22 August 1959. On average precipitation falls 115 days out of the year, and the average annual rainfall is 1,062 millimetres (42 in). With monthly percent possible sunshine ranging from 37 percent in March to 52 percent in August, the city receives 1,983 hours of bright sunshine annually.

How many hours of bright sunshine does Nanjing get each year?
What is the answer?
ANS: 1,983 hours
QUES: Zinc metal is produced using extractive metallurgy. After grinding the ore, froth flotation, which selectively separates minerals from gangue by taking advantage of differences in their hydrophobicity, is used to get an ore concentrate. This concentrate consists of about 50% zinc with the rest being sulfur (32%), iron (13%), and SiO
2 (5%). The composition of this is normally zinc sulfide (80% to 85%), iron sulfide (7.0% to 12%), lead sulfide (3.0% to 5.0%) silica (2.5% to 3.5%), and cadmium sulfide (0.35% to 0.41%).

What is froth flotation no longer used for?
What is the answer?
ANS:
unanswerable