根据句意及汉语提示, 在空白处填入适当的单词。

选词填空完成短文。

    we can't stop an earthquake(地震), but we can do things to make sure they don't destroy(毁坏) whole cities. first, it is not a ____ idea to build houses along lines where the ____ of the earth's plates(板块) join together. Second, if you think there ____ be an earthquake, it is better to build houses on rocks , not on ____ . Third, you must make the houses as ____ as possible. Weak buildings will fall down in an earthquake, but strong ones may ____ Scientists are ____ that one day an even bigger earthquake will hit the part around San Francisco(旧金山) . They call it " the big one ". However, people today are still building more ____ .The population in and around San Francisco is now ten ____ more than it was in 1906.This means that ____ there is another earthquake, a great many houses and buildings will be destroyed.

男性体细胞中的性染色体为____，能产生____种精子。女性体细胞中的性染色体为____，能产生____种卵细胞。