单项选择题______ is the main object of study of phonology.

单项选择题In ______, President Nixon met Mao Zedong and the two countries issued the Shanghai Communiqu.

单项选择题The Vietnam War started in ______ and ended in______.

单项选择题______ was the author of The Great Gatsby.

单项选择题Today, in Ireland about 93% of the population is ______.