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6 Say whether the following statements are true or false.
1 Land rigs look differently, although they consist of similar details.
2 Classified by weight, land rigs are light duty, medium duty, heavy
duty, and very heavy duty.
3 A rig can drill holes shallower than its maximum rated depth.
4 A rig cannot drill a hole at one site and be moved to another site to
drill another hole.
5 Land rigs are sometimes defined as "portable hole factories."
6 MODU is an abbreviation for mobile offshore drilling unit.
7 MODUs are not portable; they drill a well only at one offshore
site.
8 A submersible MODU floats on the water's surface when moved
from one drilling site to another.
9 The first MODU was not submersible.
10 A bottle-type rig has four tall steel cylinders (bottles) at each
corner of the structure.

7 Fill in the gaps.
d) steel g) bottom
a) tow
b) deck e) swamps h) barge

c) waters f) inland i) drilling

A fourth submersible is an _____ (1) barge rig. It has a ____
(2) hull-a flat-bottomed, flat-sided, rectangular ____ (3) box. The rig
builder places a ____ (4) rig and other equipment on the barge ____
(5). Inland barge rigs normally drill in marshes, bays, ____ (6), or
other shallow inland waters. By definition, barges are not self-
propelled; they have no built-in power to move them from one site to
another. Therefore, boats ____ (7) them to the drilling location. When

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