The xylem of ferns and conifers contains only tracheids.

　　蕨類(lèi)植物和針葉樹(shù)的木質(zhì)部?jì)H含有管胞。

　　Large proportion of xylem benefit to the water transfer.

　　葉脈中木質(zhì)部比重越大，越有利于水分的傳輸。

　　A Review of the Study on the Developmental Biology of Xylem

　　植物木質(zhì)部發(fā)育生物學(xué)研究

　　The length of the bars of the xylophone determines the different notes of the scale.

　　木琴琴鍵的長(cháng)度決定音階的不同音調。

　　Basically they use different types of Africans Traditional music instruments such as xylophone made out of wood and Djimbe drum.

　　樂(lè )團表演所用的樂(lè )器基本立足于非洲各式各樣的傳統打擊樂(lè )器，如用硬木雕挖的木琴，世界聞名的金杯鼓等。