Đọc hiểu

Ambient divers are, unlike divers who go underwater in submersible vehicles of pressure

resistant suits, exposed to the pressure and temperature of the surrounding ambient water. Of all

types of diving, the oldest and simplest is free diving. Free divers may use no equipment at all,

but most use a face mask, foot fins, and a snorkel. Under the surface, free divers must hold their

breath. Most free divers can only descend 30 to 40 feet, but some skilled divers can go as deep

as 100 feet.

Scuba diving provides greater range than free diving. The word scuba stands for self-contained

underwater breathing apparatus. Scuba divers wear metal tanks with compressed air or other

breathing gases. When using open-circuit equipment, a scuba diver simply breathes air form the

tank through a hose and releases the exhaled air into the water. A closed-circuit breathing device,

also called a rebreather, filters out carbon dioxide and other harmful gases and automatically

adds oxygen. This enables the diver to breathe the same air over and over. In surface-supplied

diving, divers wear helmets and waterproof canvas suits. Today, sophiticated plastic helmets

have replaced the heavy copper helmets used in the past.These divers get their air from a hose

connected to compressors on a boat. Surface-supplied divers can go deeper than any other type

of ambient diver.

Question 1: Ambient divers are ones who

A. can descend to extreme depths

B. use submersible vehicles

C. use no equipment

D. are exposed to the surrounding water

Question 2: According to the passage, a free diver may use any of the following

EXCEPT

A. a rebreather

B. a snorkel

C. foot fins

D. a mask

Question 3: According to the passage, the maximum depth for free divers is around

A. 40 feet

B. 100 feet

C. 200 feet

D. 1,000 feet

Question 4: When using closed-circuit devices, divers

A. exhale air into the water

B. hold their breath

C. breathe the same air over and over

D. receive air from the surface

Question 5: What does the word “descend” in the paragraph probably mean?

A. move to a lower level

B. climb to a higher place

C. swim on the river bed

D. go up and down slowly

Question 6: The word “This” in bold in paragraph 2 refers to

.

A. filtering out carbon dioxide

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