certain period的用法和樣例：
例句
- The literature of a period reflects its values and tastes.
某一時(shí)期的文學(xué)可反映出該時(shí)期的價(jià)值觀(guān)念和審美觀(guān)念。 - The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded on a seismogram at a certain period.
地震級別是根據某一時(shí)期震動(dòng)圖記錄的地震波振幅的對數值計算的。
