上个星期。

The term '上个星期' (shàng ge xīngqī) in Chinese literally translates to 'previous/last week'. Let's break down its components: * **上 (shàng):** This character has a broad range of meanings, including 'up', 'above', 'superior', and also 'previous' or 'last'. In this context, it functions to denote something that precedes in time. * **个 (ge):** This is a very common measure word (classifier) in Chinese, used for a wide variety of nouns, including periods of time like 'week'. It doesn't carry significant semantic meaning itself but is grammatically necessary. * **星期 (xīngqī):** This word means 'week'. It is composed of two characters: * **星 (xīng):** Means 'star'. * **期 (qī):** Means 'period of time', 'term', or 'phase'. The combination '星期' (xīngqī) literally means 'star period'. This naming convention is deeply rooted in ancient Chinese astronomy and calendar systems. Traditionally, the seven days of the week were associated with the seven luminaries (七曜 - qī yào), which included the Sun (日), Moon (月), and the five naked-eye planets: Mars (火星), Mercury (水星), Jupiter (木星), Venus (金星), and Saturn (土星). Each day was named after one of these celestial bodies. While '星期' itself is a more generalized term for 'week', its components reflect this ancient astronomical understanding of time. Therefore, '上个星期' combines the concept of 'previous' with the established term for 'week' to clearly and concisely refer to the week immediately preceding the current one. This construction is a standard way to express past time periods in Chinese, following a pattern seen in terms like '上个月' (shàng ge yuè - last month) and '去年' (qù nián - last year, where '去' also implies past).