Multiple-choice cloze
For questions 1-8, read the text below and decide which answer (A, B, C or D) best fits each gap.
The humble pencil owes its existence to a storm. Some time in the sixteenth century, so the story goes, a violent gale a tree in Borrowdale, in the English Lake District, and exposed a seam of a black, glistening substance beneath its roots. Local shepherds soon found it ideal for their sheep, and before long the material, then thought to be a form of lead, was finding its into London workshops. So was it that the mine was flooded between excavations to deter thieves, and miners were searched as they left their shifts. For two centuries, Borrowdale remained the only known source of graphite pure enough to be sawn into sticks, and English pencil-makers enjoyed what to a monopoly. It was not until the 1790s, when war had cut France from English supplies, that a French engineer devised a way of mixing powdered graphite with clay and firing it in a kiln. His method had the added advantage that the hardness of the lead could be varied to the proportion of clay used. Today, billions of pencils are produced every year, yet few of the people who use them would a thought to the storm that started it all.
เคล็ดลับ: คลิกหมายเลขช่องว่างเพื่อไปยังคำถามนั้น.