I. Read the following passage and explain the use of each article in it
In the 1880s, Alphonce de Candolle, a Swiss botanist, published a book entitled ‘Origin of Cultivated Plants’, based on data he had gathered from many sources. He deduced that cultivated plants probably originated in areas where their wild relatives grow. In 1916, N.I. Vavilov, a Russian botanist and geneticist, began a follow-up of de Candolle’s work and modified his conclusions. Vavilov became persuaded, as a result of his research, that most cultivated plants differ appreciably from their wild relatives. He also concluded that dispersal centres of cultivated plants are characterized by the presence of dominant genes in plant populations, with recessive genes becoming apparent towards the margins of a plant’s distribution…
II. Use a/an, or the articles where necessary in the following text
Nothing is more important to ___ relationship of ___ humans to ___ environment than ___ cultivated plants that provide ___ sources of ___ food, ___ fiber, ___ animal forage, and ___ medicines. ___ cultivated plants have been developed in nearly all ___ climatic regions of ___ earth and reflect ___ wide diversity of ___ environments occupied by ___ humans. ___ cultivated plants appear to have originated in ___ six major regions: Near Eastern (wheat, carrots, apple), Chinese (soybean, cucumber, peach), African (yam, cotton, coffee), South Asian and Pacific (rice, sugar, cane, citrus fruits), North American (sunflower, tobacco), and South and Central American (white Irish potato, squash, pineapple). ___ plants originating in these ___ regions are now grown throughout ___ world. Today’s ___ most important cultivated plants are ___ tiny fraction of ___ thousands of species used by ___ peoples around ___ world; preserving ___ knowledge of ___ useful plants held by ___ traditional societies is ___ major challenge for this ___ generation of ___ botanists.
LISTENING COMPREHENSION
I. You are going to hear three pieces of information about the ferns. Before listening, look through the words in the box below. Use a dictionary or discuss their meanings in class if necessary.
to scrape off
patch
inadvertently
to frustrate
to float
megaphyl
frond
pleated
clover
humus
opinion poll
to accumulate
deposit
to inhibit
coal
Carboniferous period
horse tail
club moss
swampy area
bacteria-mediated decay