We have always been warned of the dangers of forest fires. They cause _____ 85 _____ to a forest. They kill many plants and animals in an eco-system, which is a group of living things and their environment. But have you ever heard of a forest fire that can be _____86_____  for a forest? People start some of the fires with a special reason to actually do good to the eco-system.
In fact, fires are a natural part of any eco-system. Without fires, the oldest and largest trees would stop sunlight from reaching the forest floor. Fires can _____87_____ some of these old trees. When the trees die, they provide something good for the earth. New trees can grow strong and healthy in their place.
Some trees even need fires to grow. These trees hold their seeds (种子) inside. Heat from a fire allows the coat of the seeds to open up. Then the seeds fall to the ground and have the _____88____ to grow/
Scientist, who know about nature’s needs, start some of these fires, called controlled burns. A fire is started and kept under control. This way, the fire does not spread out of the area or _____89_____ a after forest fires, they can go hungry _____90_____ their food has been damaged in the fire. Small, controlled fires mean than animals will not have to move far to find food. After some time, small plants begin to grow. Animals return soon after the plants return. This _____91_____  makes an eco-system.
So the next time you hear about a forest fire, think about the good as well as the bad. It may take a new eco-system a while to return, but it will likely come back stronger and healthier than ever.

Choose the words or expressions and complete the passage (选择最恰当的单词或词语，完成短文)
1．We have always been warned of the dangers of the forest fires. They cause     1   to a forest. They kill many plants and animals in an eco-system, which is a group of living things and their environment. But have you ever heard of a forest fire that can be     2    for a forest?
2．People start some of the fires with special reasons to actually do well to the eco-system.
3．In fact, fires are a natural part of any eco-system. Without fires, the oldest and largest trees would stop sunlight from reaching the forest floor. Fires can       3      some of these old trees. When the trees die, they provide something good for the earth. New trees can grow strong and healthy in their place.
4．Some trees even need fires to grow. These trees hold their seeds(种子) inside. Heats from a fire allow the coat of the seeds to open up. Then the seeds fall to the ground and have the 4 to grow.
5．Scientists, who know about nature’s needs, start some of these fires, called controlled burns. A fire is started and kept under control. This way, the fire does not spread out of the area or 5   a large space of the forest. Fires can be dangerous for animals. Even when animals continue to live after forest fires, they can go hungry   6    their food has been damaged in the fire. Small, controlled fires mean that animals will not have to move far to find food. After some time, small plants begin to grow. Animals return soon after the plants return. This   7 makes an eco-system.
6．So the next time you hear about a forest fire, think about the good as well as the bad. It may take a new eco-system a while to return, but it will likely come back stronger and healthier than ever.

We have always been warned of the dangers of forest fires. They cause _____ 85 _____ to a forest. They kill many plants and animals in an eco-system, which is a group of living things and their environment. But have you ever heard of a forest fire that can be _____86_____  for a forest? People start some of the fires with a special reason to actually do good to the eco-system.

In fact, fires are a natural part of any eco-system. Without fires, the oldest and largest trees would stop sunlight from reaching the forest floor. Fires can _____87_____ some of these old trees. When the trees die, they provide something good for the earth. New trees can grow strong and healthy in their place.

Some trees even need fires to grow. These trees hold their seeds (种子) inside. Heat from a fire allows the coat of the seeds to open up. Then the seeds fall to the ground and have the _____88____ to grow/

Scientist, who know about nature’s needs, start some of these fires, called controlled burns. A fire is started and kept under control. This way, the fire does not spread out of the area or _____89_____ a after forest fires, they can go hungry _____90_____ their food has been damaged in the fire. Small, controlled fires mean than animals will not have to move far to find food. After some time, small plants begin to grow. Animals return soon after the plants return. This _____91_____  makes an eco-system.

So the next time you hear about a forest fire, think about the good as well as the bad. It may take a new eco-system a while to return, but it will likely come back stronger and healthier than ever.

1.A) illness     B) difficulty      C) damage       D) flood

2. A) helpful    B) powerful      C) harmful       D) awful

3. A) take the place of    B)  get ready for     C)  be bad for      D) get rid of

4.A) time       B) water       C) chance       D) skill

5.A) discover    B) cover       C) but          D) waste

6. A) because    B) although      C) but         D) so

7.A) almost     B) again        C) never      D) even

What would happen if you tried to blow a soap bubble in freezing weather? Would it freeze solid(固体) and fall to the ground? Would you have to hit it to break it? These questions happened to me on a cold winter day. It was too cold to play in the snow, but it was a perfect time to experiment with blowing frozen bubbles.
To blow frozen bubbles, I used dishwashing soap and a drop of glycerin（甘油） to make it even better. I chose a place out of the wind, and blew bubbles the same way I always do. I watched to see what would happen. Here’s what I learned.
If the temperature is low enough, the skin of the bubbles frosts over (结霜), becoming cloudy instead of clear. And what about those rainbow swirls（旋转） you see in soap bubbles? The rainbow colors stay even when the bubbles frost, but they don’t swirl anymore. The bubbles still stay in the air. They don’t fall to the ground any faster than they would on a warm summer day.
When these frozen bubbles break, they don’t turn into small water drops as summer bubbles do. They turn into flashing rainbow confetti（碎屑） and move slowly to the ground. Sometimes a frozen bubble will roll across the snow without breaking. If nothing disturbs the bubble, it may stay there for a long time. Sometimes I could catch a bubble and hold it until the heat of my hand made it pop.
I learned another thing about blowing frozen bubbles. It’s so interesting that I want to try it again next year.
【小题1】It is the perfect time to blow frozen bubbles on a ___________day.

We have always been warned of the dangers of forest fires. They cause _____ 85 _____ to a forest. They kill many plants and animals in an eco-system, which is a group of living things and their environment. But have you ever heard of a forest fire that can be _____86_____  for a forest? People start some of the fires with a special reason to actually do good to the eco-system.

In fact, fires are a natural part of any eco-system. Without fires, the oldest and largest trees would stop sunlight from reaching the forest floor. Fires can _____87_____ some of these old trees. When the trees die, they provide something good for the earth. New trees can grow strong and healthy in their place.

Some trees even need fires to grow. These trees hold their seeds (种子) inside. Heat from a fire allows the coat of the seeds to open up. Then the seeds fall to the ground and have the _____88____ to grow/

Scientist, who know about nature’s needs, start some of these fires, called controlled burns. A fire is started and kept under control. This way, the fire does not spread out of the area or _____89_____ a after forest fires, they can go hungry _____90_____ their food has been damaged in the fire. Small, controlled fires mean than animals will not have to move far to find food. After some time, small plants begin to grow. Animals return soon after the plants return. This _____91_____  makes an eco-system.

So the next time you hear about a forest fire, think about the good as well as the bad. It may take a new eco-system a while to return, but it will likely come back stronger and healthier than ever.

85. A) illness     B) difficulty      C) damage       D) flood

86. A) helpful    B) powerful      C) harmful       D) awful

87. A) take the place of    B)  get ready for     C)  be bad for      D) get rid of

88. A) time       B) water       C) chance       D) skill

89. A) discover    B) cover       C) but          D) waste

90. A) because    B) although      C) but         D) so

91. A) almost     B) again        C) never      D) even