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4th Grade English

Vietnamese Olympiad of English - Grade 4

Choose the best answer for the following questions.

Lesson 0.2 Objective Words (Level 4A)

invisible	[in-'viz-uh-buhl] adj - cannot be seen by the eye; not visible. Goodwill is an invisible asset to a business.
magma	['mag-muh] noun - molten material beneath or within the earth's crust, from which igneous rock is formed.
diamond	['dahy-muhnd] noun - a nearly pure, extremely hard form of carbon, naturally crystallized in the isometric system.
outermost	['ou-ter-mohst] adj - farthest out; remotest from the interior or center. The outermost limit of the city is dessert.
predict	[pri-'dikt] verb - to declare or tell in advance; prophesy; foretell. The weatherman's job is to predict the weather.
temperature	['tem-per-uh-cher] noun - a measure of the warmth or coldness with reference to some standard value. In a hot summer, the temperature in Houston can be as high as 100 °F.
violent	['vahy-uh-luhnt] adj - acting with or characterized by uncontrolled, rough force. A violent earthquake destroyed the small town completely.
dormant	['dawr-muhnt] adj - asleep; in a state of rest or inactivity. The lecturer's sudden shout woke the dormant audience.

A volcano is a natural wonder that can be both harmful and helpful to living things. Read the article about volcanoes.

Volcano!

It begins when ____ 1 ____ gases escape from an opening at the mountain’s top. Then, a huge explosion fills the air. A cloud of steam, ash, and burning rock bursts out of the crater created by the blast. The sky becomes dark. Dust and ash block the Sun. Hot melted rock gushes over the sides of the crater and travels down the mountain. A volcano has erupted.

A.  poisonous
B.  dormant
C.  invisible
D.  colorful

A Volcano Is Born

Active volcanoes, like the one described above, are often large mountains. When a volcano is born, however, it starts out as a crack in the surface of Earth. Hot, melted rock from deep inside Earth rises and pushes through this crack. This melted rock, called ____ 2 ____, forces its way out. The magma is now called lava. The lava cools and becomes hard. Over many years, the dried lava builds up into layers. After a while, these layers form a tall mountain. These volcanic mountains can form on dry land or under the sea on the ocean floor. Volcanic mountains born under the ocean can become islands. People think the island of Hawaii was formed this way.

Most volcanoes form along the largest cracks in Earth’s surface. Earth’s ____ 3 ____ layer (the crust) is made up of sections called plates. Plates float slowly on the liquid magma. The world’s continents are on these plates. As the plates move, melted rock can push its way through the places where they meet. A string of volcanoes has formed along the edges of a large plate. This area is known as the Ring of Fire. California and Alaska are located along the Ring of Fire.

A.  crack
B.  magma
C.  lava
D.  crust

A.  invisible
B.  innermost
C.  internal
D.  outermost

New Land Is Formed

Dried lava can add new land around a volcano. This can happen suddenly or over many years. Volcanoes can erupt ____ 4 ____, covering the surrounding area with rocks and ash. Other volcanoes are gentle, letting lava trickle slowly out of the opening and down the mountainside. Kilauea and Mauna Loa, two volcanoes on the island of Hawaii, usually give plenty of warning before they spew hot lava. Their lava sometimes adds new land to the island.

Detecting Volcanoes

Long ago, people had no warning that a volcano was about to erupt. Because of this, many people died. Much has changed thanks to scientists who study volcanoes. Today, scientists almost always know when a volcano may erupt. They use instruments that measure escaping gas and earthquake-like tremors in the earth. Scientists use computers to check for bulges in the sides or near the top of a volcano. Scientists around the world are always at work ____ 5 ____ when the next volcano might erupt.

A.  violently
B.  mildly
C.  slowly
D.  outermostly

A.  concealing
B.  hiding
C.  predicting
D.  recording

Harmful or Helpful?

Volcanoes can be harmful. Hot gases and lava hurt living things. They can destroy crops and wipe out homes and towns. ____ 6 ____ can drop when clouds of ash block out the sun for days at a time. Daytime can seem like night. When this happens, more crops die. Sometimes, people have to leave their homes because of the ash in the air. This ash makes it hard for people and animals to breathe.

Volcanoes can also be helpful. Farmers use soil that comes from volcanoes. Dried lava holds useful minerals that help plants grow. Lava is also used to make soap. Volcanic rocks are used as building materials, since they are easy to find and easy to work with. Gold, silver, and diamonds [7] have also been found in and around old volcanoes. Hot water and steam from volcanoes can be used to make electricity and to grow food in greenhouses. Many people will visit an area to watch a volcano spill lava or let out steam. A volcano can be a beautiful sight when seen from a distance.

Active volcanoes allow steam, gas, and lava to escape, but ____ 8 ____ volcanoes do not show these signs of erupting. Around these volcanoes, new plants have sprouted, and animals once again roam the hillside among the ash and dried lava. Life has returned.

A.  Pressure
B.  Horizon
C.  Elevation
D.  Temperatures

7. What is a diamond?

A.  a kind of metal
B.  a hard, bright precious stone
C.  a chemical substance making crops grow better
D.  a dark rock with a lot of holes

A.  invisible
B.  dormant
C.  active
D.  outermost

9. All these are ways that a volcano can be helpful, except which?

A.  Lava can be used for making soap.
B.  Dried lava contains diamonds that help plants grow.
C.  Volcanic rocks are used as building materials.
D.  Hot water and steam can be used to make electricity and grow crops in greenhouses.

10. Which are the ways that a volcano can be harmful?

A.  Crops, homes, and towns can be wiped out.
B.  Ash in the air makes it difficult for people and animals to breathe.
C.  Hot gases and lava harm living things.
D.  all of them