Ответы на задания English Tenses (ИРНИТУ)

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DRILLING FOR OIL – PAST AND PRESENT

Long ago, wells (1) were dug (dig) in the ground using percussion drilling. A heavy wooden cutting tool (2) __________(suspend) by a rope from a pulley on a wooden tripod. The tool (3) __________(pull up) by hand or steam engine, and then it (4) __________(drop) into the hole. The rock (5) __________ (break) by the weight of the tool. The maximum depth was 70 metres.

Nowadays, much deeper oil wells of 700 m (6) __________(dig) using a method called rotary drilling. A sharp drill bit (7) __________ (suspend) by a drill string from a pulley on a steel derrick. The drill bit (8) __________ (rotate) in the hole by a powerful engine. The rock (9) __________ (break) by the rotation of the drill bit.

Now there is also a new method of drilling which (10) ______ (cut) the rock using lasers. No cutting tool or drill bit (11) __________ (use). Instead, the rock (12) __________(split) by beams of high-energy light. A fibre-optic cable (13) __________ (carry) the light from the lasers on the surface down the hole to a set of lenses. The lenses then (14) __________ (focus) the light to a sharp point on the rock face, which (15) __________ (cut) almost 100 times faster than by a drill bit.

As a result, the cost of drilling (16) __________ (reduce), and drilling jobs (17) __________ (complete) much more quickly.