According to the writer, people start to be interested in possible female-dominant societies in the past be cause ______.

单项选择题The author believes that more houses were bought last year because______.

单项选择题The weekly unemployment data show that ______.

单项选择题The underlined word upbeat in paragraph 2 probably means ______.

单项选择题The author discusses computing machines in the first paragraph primarily in order to ______.

单项选择题The author implies that scientists develop a healthy skepticism because they are aware that ______.