1 . ________ is known to us that smoking is harmful to our health. (用适当的词填空)

2 . My mother makes __________ a rule that everyone must go to bed before 9 p. m. (用适当的词填空)

3 . Today, it is estimated that about 60 percent of domestic rice consumption in China is comprised of crops generated from Yuan’s hybrid strains. (英译汉)