Usually only found in tropical areas, malaria is spread by female Anopheles mosquitoes, and (1)
they have a very developed system for finding people and animals to bite. The female mosquito
which carries the malaria parasite has a variety of sensors designed to track (2) its prey. These
include chemical sensors, visual sensors and heat sensors. Using the first of (3) these, mosquitoes
can sense, almost smell, carbon dioxide and lactic acid up to 36 metres away. Mammals and birds
give off these gases as part of (4) their normal breathing, and the mosquitoes home in on them. (4a)
It seems that certain chemicals in human sweat also attract mosquitoes. People who do not sweat
very much tend to get bitten much less than people who do.
Mosquitoes do not only smell their human prey, they also see (5) them. If a person is wearing clothing
that contrasts with their background, and especially if that person moves while wearing that clothing,
mosquitoes can notice the colour contrast and the movement and are drawn to (6) this. Anything that
moves is probably alive and therefore full of blood, so this is a good technique for the mosquito. These
terrible insects can also feel their prey by using a kind of heat sensor. Mosquitoes are able to detect
heat, so (7) they can find warm-blooded creatures easily once (8) their sight and sense of smell have
brought (9) them close enough.
As you can see, evolution has unfortunately equipped the mosquito with a highly effective system of
prey location.
Pronoun-type word
1) they
2) its
3) these
4) their
5) them
6) this
7) they
8) their
9) them
refers to.....
Task 1: read the passage below and fill-in the following table
Smallpox, also known by its Latin name variola, is a serious, contagious disease. (1) It is
often fatal. There is no specific treatment for smallpox, and the only prevention is
vaccination. The name smallpox comes from the Latin word for “spotted” and refers to the
raised bumps that appear on the face and body of an infected person. Even if a victim of
smallpox survives, (2) these can lead to permanent scarring. There are two main types of
smallpox. Variola major is the more severe and more common form of smallpox.
Historically, (3) it has an overall fatality rate of about 30%. Variola minor is the less common
form of smallpox, and (4) this a much less severe disease, with death rates historically of
1% or less.
Pronoun-type word
refers to.....
1) It
2) these
3) it
4) this
Task 1: read the passage below and fill-in the following table
In 1965, Frank Herbert, a 45 year old American, completed a science fiction novel set on a
desert planet in a futuristic universe. (1) He called his novel Dune. The novel was rejected
by more than twenty publishers before a minor publishing house in Philadelphia decided to
take a chance with (2) it. (3) It was the right decision. Dune turned into the best-selling
science fiction novel ever, and the five books in the Dune saga became the most popular
science fiction series of all time. In the year of (4) its publication Dune won the prestigious
Nebula Award, which is voted and presented by the Science Fiction Writers of America for
the best science fiction novel of the year. In 1966, Dune shared first place to win the Hugo
Award. (5) This is given by the World Science Fiction Society and is even more prestigious
than the Nebula.
Dune is similar to Robert Heinlein's 1961 novel Stranger in a Strange Land, in that (6)
its characterizations and the intricacy of the plot show a more literary approach to the writing
of science fiction novels. (7) These were often dismissed by serious writers as having no
literary value and (8) it was a widely held belief that the only thing a science fiction novel
needed to succeed was a compelling and original technological idea. The characters in a
pre-1960’s science fiction novel were usually less important than the technology: (9)
they served only as users or victims of the technology. Dune helped change all that and
bring science fiction writing closer to the mainstream.
Pronoun-type word
1) He
2) it
3) It
4) its
5) This
6) its
7) These
8) it
9) they
refers to.....