李世民 近體詩 五律 聲律 平仄 黏對 四聲遞用 Li Shih-ming Tang dynasty's poem Ching-ti Shih Five syllable poem Rhymes and tones Level and oblique tones by turns in a sentence Level and oblique tones by turns in a poem Eight lines Phenomenon of using the four tones by turns in one line or one poem The level tone Falling-rising tone Falling tone Entering tone