7 Fill in the correct word derived from the words
in brackets.
The 1) ..........
(define) of a pest is
any type of insect or
animal that is so 2)
(number) that it
becomes a problem
to humans. In the
home, pests such as
rats, cockroaches,
termites and fleas can be very 3)
(annoy), and
their 4) ................... (resist) to poisons makes them difficult
to get rid of. For farmers, locusts are one of the most 5)
(destroy) pests in 6) ... (exist). They
are extremely fast breeders, and their 7) ............. (able)
to consume leaves quickly means that they can wipe out
entire crops within hours. Scientists are working on the 8)
(develop) of an 9) ........ (effect) means
of controlling this menace, but so far a completely success-
ful 10)
...... (solve) has not been found.​