Our knowledge of space is increasing__________

A

day after day:

日复一日地

例句与用法:
1. Day after day she waited in vain for him to telephone her.
日复一日, 她徒劳地等待他的电话.

2. Day after day she wanders on until at length on the high, chalky table-lands.
一天又一天，她漫无目标地流浪，最后来到一个白垩高地。

3. Day after day, the scientists worked hard in the laboratory.
那些科学家们日复一日在实验室中努力工作着。

英英解释:
形容词day after day:

1. occurring or done each day
同义词：daily, day-to-day, day-after-day, every day

副词day after day:

1. for an indefinite number of successive days
同义词：day in day out

day by day:

n. 一天天

例句与用法:
1. It is getting warmer day by day.
天气一天天暖和起来。

2. The patient's condition is improving day by day.
病人的病情逐日好转。

3. Day by day she learnt more about her job.
她日益了解自己的工作了.

4. Repulse after repulse failed to deter Alec, who persisted day