在一列数中，若后一个数都比相邻的前一个数相差同一个数，我们称这列数为等差数列．比如：3，7，11，15，19…现有5个数2.5，A，□，C，10.9组成等差数列，那么A=____ ．

根据电解水实验装置图回答下列问题：

    Does the age gap matter in a relationship?

    The love story of French President Emmanuel Macron and Brigitte Trogneux, 24 years his senior, has aroused heated discussion on age differences ____ relationships. Does age matter or should love prevail(战胜) over all?

    I find ____ a very heartwarming love story. Not just this couple,____any couple - what does age difference matter after all? If they love each other,____ ( devote) to the relationship and work on making it strong, that is what____ (count).

    It is nearly impossible for Chinese women to accept Macron's relationship. It is  ____ (common) for older men to marry younger women, but for an older woman to marry a younger man is often seen as ____ (appropriate). If you get along well, go for it, it's your life and life is way too short____ (let) a potential soul mate get away because of what you think others would say. I think it really doesn't matter. It is involved in the ____ (devote) of the people and how well they enjoy each other's company is important along with supporting each other ____(emotion), financially etc....

一个地区的人口自然增长率是由（　　）决定的．

下列词语中加线字的注音全都正确的一组是(      )