从气象原理来看，三伏天期间，我国大部地区被副热带高压或大陆高压控制，一般高压系统比较稳定少动，容易长时间控制一个地区，且控制区域内盛行下沉气流，不利于热量扩散，此时太阳仍然直射北半球，热量累积，容易出现高温天气。

单词 “period” 可以表示 “一段时间”，还可以用来表达 “阶段，时期”，学校中的 “课时”。在美式英语中，它还有 “句号” 的意思。看视频，用一分钟时间学习 “period” 的这几个常见用法。 用法总结 1 “Period” 是名词 ...

While promoting medical innovation and expanding access to advanced treatments, China has also strengthened efforts to ensure drug prices remain fair and sustainable. Since 2018, the country has ...

Stage, phase, spell, period 用法浅析 Play audio file. 内容简介. 名词 “stage, phrase, spell, period” 都可以用来表示 “一段时间”，但它们的具体用法相同吗？本期节目对这四个名词进行逐一讲解。 欢迎你加入并和我们一起讨论英语学习的方方面面。

BEIJING, July 24 (Xinhua) -- During the 14th Five-Year Plan period (2021-2025), China's medical insurance authority adopted multiple measures to ensure reasonable pricing of medicines, a senior ...

BEIJING, July 15 (Xinhua) -- Despite rising challenges and external uncertainties, China achieved steady economic growth in the first half of the year (H1) and is actively taking steps to maintain ...