时间:2019-02-15 作者:英语课 分类:英语时差8,16


英语课

 Because chlorophyll is the chemical responsible for making leaves green, its absence allows chemicals such as carotinoids, xanthophylls, and others to give leaves their orange, yellow, and various other colors. As trees stop producing chlorophyll, they start producing sugars and amino acids that act as a sort of antifreeze to protect plants from the winter cold. Meanwhile, nutrients 1 drain from the leaves, through the stems, and eventually into the roots, where they remain for the winter. When the nutrients have left the leaves, all that remain are cell walls and nutrient-depleted protoplasm. Since all that now holds leaves to a tree are brittle 2, dry, and easily broken veins 3, a gust 4 of wind is enough to tear leaves from the tree and send them fluttering to the ground. When dead leaves break away, they leave behind waxy 5 cells that form a small bud called a bundle scar. When warm weather returns, each scar will give rise to a newly born leaf.



n.(食品或化学品)营养物,营养品( nutrient的名词复数 )
  • a lack of essential nutrients 基本营养的缺乏
  • Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》
adj.易碎的;脆弱的;冷淡的;(声音)尖利的
  • The pond was covered in a brittle layer of ice.池塘覆盖了一层易碎的冰。
  • She gave a brittle laugh.她冷淡地笑了笑。
n.纹理;矿脉( vein的名词复数 );静脉;叶脉;纹理
  • The blood flows from the capillaries back into the veins. 血从毛细血管流回静脉。 来自《简明英汉词典》
  • I felt a pleasant glow in all my veins from the wine. 喝过酒后我浑身的血都热烘烘的,感到很舒服。 来自《简明英汉词典》
n.阵风,突然一阵(雨、烟等),(感情的)迸发
  • A gust of wind blew the front door shut.一阵大风吹来,把前门关上了。
  • A gust of happiness swept through her.一股幸福的暖流流遍她的全身。
adj.苍白的;光滑的
  • Choose small waxy potatoes for the salad.选些个头小、表皮光滑的土豆做色拉。
  • The waxy oil keeps ears from getting too dry.这些蜡状耳油可以保持耳朵不会太干燥。
学英语单词
2-methylpindolol
a full plate
Adaplex
alkaline geochemical barrier
always afloat
asplenium pekinensis hance
ball cartridge
bartolotta
befathered
betare oya
blued chopping knide with wooden handle
Bohr quantization condition
cable sheave
charles v
cheatwood
Checkwriting
chemical pruning
claim notices
coalgas
cognitive test
combined tea-refining machine
continuous indication
copper(ii) phosphate
copy ... to
crank extension
cross-debt
delivery of check
driver pinion
elatigenin
electronic theodolite
elliptocytosis-1
emergency air bottle
etherealizes
final great circle course
Flueggea suffruticosa
fodder plant
genus venuss
glandis septum
graphic appraisal methods
hard magnetic materials
HICAT
homeocyte
host preparation facility
identifiable parameter
in installments
intended vessel
interventure
Jordanianizes
Kyrle
labial fold
lectorship
lindbloms
lipoteichoic acids
magnet roller
maintenance runaway
merrs
Mildred Didrikson
mitoclomine
molybdenum diiodide
Mouzay
multiband post acceleration tube
neoliberalist
no help for it
nod at
norvegicus
oil skipper
painted turtles
parasitopolis
patriotically
pinnatella ambigua
Poiseuille law
price restraint
Primula crocifolia
proper vector
recaps
recyclates
reinforcings
safeways
Scutellaria caudifolia
self-explanatory
sequential by key processing
seroalbumin human placental
silicon filament
sorting office
starry sturgeon
Stepnogorsk
supplementary accounts
tilted fault block
total usage amount
transmission velocity
Tuncurry
undastan
undecidable theory
use it or lose it
wake up to
waste caustic
wax-like
weighted accumulator
wet katathermometer
wood grain finish
wood substance
X-ray image receptor