下列对抗日根据地文化建设的理解，最能体现'统一战线'特征的是：

以下哪种行为不利于建立有效的沟通？

Choose the correct temporal adverb: Newspapers became mainstream ______ the 19th century, while television dominated ______ the mid-20th century.

在Java中，若Student类实现了Comparable接口并重写了compareTo方法，以下哪个选项正确描述了compareTo方法的返回值含义？

In the context of natural selection, what does the decrease in male mortality rate imply for the population?