他的情绪似乎在兴奋和焦虑之间交替。

His mood seems to ___alternate between excitement and anxiety.

课程表设计为每周在科学和文学项目之间交替进行。

The schedule is designed to ___alternate between science and literature projects each week.

在这个地区，天气往往在晴天和大雨之间交替。

In this region, the weather tends to ___alternate between sunny days and heavy rain.