The xylem of ferns and conifers contains only tracheids. 蕨类植物和针叶树的木质部仅含有管胞。 Large proportion of xylem benefit to the water transfer. 叶脉中木质部比重越大，越有利于水分的.传输。 A Review of the Study on the Developmental Biology of Xylem 植物木质部发育生物学研究 The length of the bars of the xylophone determines the different notes of the scale. 木琴琴键的长度决定音阶的不同音调。 Basically they use different types of Africans Traditional music instruments such as xylophone made out of wood and Djimbe drum. 乐团表演所用的乐器基本立足于非洲各式各样的传统打击乐器，如用硬木雕挖的木琴，世界闻名的金杯鼓等。 上一篇：玩的英文 下一篇：health的形容词不健康的 |