字神帝國英語天地

By the start of the Great War the airship had been developed into two main types - rigid and non-rigid (technically, the latter is more accurately described as pressure-rigid). Cylindrical in cross-section, both were given buoyancy by gas and motion by engine-driven propellers and were controlled by vertical rudders and horizontal elevators.

✙ 雪花

對於一片六角形雪片來說，由於它表面曲率不等(有凸面、平面和凹面)，各面上的飽和水汽壓力也不同，因此產生了相互間的水汽密度梯度，使水汽發生定向轉移。水汽轉移的方向是凸面→平面→凹面，也就是從曲率大的表面，移向曲率小的表面。六角形雪片六個棱角上的曲率最大，邊棱部分的平面次之，中央部分曲率最小。這樣，就使六角形雪片一直處在定向的水汽遷移過程中。由於棱角上水汽向邊棱及中央輸送，棱角附近的水汽飽和程度下降，因而產生昇華現象。中央部分由於獲得源源不斷的水汽而達到冰面飽和，產生凝華作用。這種凝華結晶的過程不斷進行，六角形雪片逐漸演變成為六棱柱狀雪晶。

✙ Troy 特洛伊

“荷馬史詩”包括《伊利亞特》和《奧德賽》兩部長詩，被認為是古希臘最偉大的作品，也是歐洲文學中最古老、最傑出的敘事詩。相傳史詩的作者是古希臘盲詩人荷馬。他生於愛奧尼亞(今土耳其西海岸)，生存年代約是西元前8世紀的後半葉。

✙ 汞污染

汞是在常溫下唯一呈液態的金屬元素。在自然界裡大部分汞與硫結合成硫化汞(HgS)，亦稱“辰砂”或“朱砂”，廣泛地分佈在地殼表層。辰砂及其多晶體偏辰砂是主要的含汞礦源。隨著自然的演化，環境的各個因素中都可能含有汞，形成汞的天然本底。

✙ 黑洞

“黑洞”很容易讓人望文生義地想像成一個“大黑窟窿”，其實不然。所謂“黑洞”，就是這樣一種天體：它的引力場是如此之強，就連光也不能逃脫出來。

✙ Rainforest Layers

High temperature and rainfall production, more or less uniform throughout the year, characterize the rainforest worldwide. The water that is required to maintain this environment also threatens its existence. If left uncontrolled, the water that constantly bombards the soil would leech out most of the valuable nutrients. Plants and animals in this environment have developed adaptations to deal with the constant deluge and to compete successfully for nutrients.