Below 600 feet ocean waters range from dimly lit to completely dark.

单项选择题She has such exceptional abilities that everyone is jealous of her.

单项选择题The old concerns lose importance and some of them vanish altogether;

单项选择题In 1861 it seemed inevitable that the Southern states would break away from the Union.

单项选择题Peter is experiencing a difficult period in his life.

单项选择题Thus our conviction is reinforced that only social revolution can really solve the problems of the people.