The _________ cycle of life and death is a subject of interest to scientists and philosophers alike.

单项选择题Rumours are everywhere, spreading fear, damaging reputations, and turning calm situations into _________ ones.

单项选择题Fiber-optic cables can carry hundreds of telephone conversations _________.

单项选择题Whether you live to eat or eat to live, food is a major _________ in every family’s budget.

单项选择题Now a paper in Science argues that organic chemicals in the rock come mostly from _________ on earth rather than bacteria on Mars.

单项选择题There is much I enjoy about the changing seasons, but my favorite time is the _________ from fall to winter.