1 . A 2020 study in the journal Science concluded that marine heat waves have increased more than 20-fold as a result of climate warming. The authors found that in the first decade after satellites began recording ocean temperatures (i.e., after 1981), there were 27 large marine heat waves, with an average duration of 32 days and an average peak temperature anomaly of 8.5°F; in the 2010s, there were 172, which lasted 48 days on average with an average peak temperature almost 10°F above normal.

Much remains unclear about marine heat waves. For example, explains Nicholas Bond, research scientist at the University of Washington and Washington’s state climatologist, there is the question of why so many persist for weeks or months. “There must be something else going on that helps maintain them,” he says. He notes that one explanation is that as the ocean surface warms, it radiates heat into the atmosphere that prevents cloud cover from forming, exposing the seawater to increased sunlight and further warming.

However, enough is known about marine heat waves for scientists to be gravely concerned about their potential impacts. Of special note is the fact that those impacts can last long after the heat waves have disappeared. After three years of the Blob, the waters of the northeastern Pacific began to cool in 2016; but years later, scientists are still determining the extent to which the region’s ecosystem is likely to return fully to its pre-Blob status. Similarly, notes Scannell, who is a data scientist with Jupiter Intelligence, Inc., following the 2010-11 Western Australia event, “lots of kelp(巨藻) forests died, and it takes literally decades for those ecosystems to bounce back”.

Eric Oliver, a scientist from Dalhousie University in Nova Scotia, Canada, expressed his own opinion about the potential impact of the heat waves in tropical waters. “I think that’s really a tough issue,” he says. Life in the tropics, he notes, is adapted to “quite a narrow range of temperatures. So that’s where things can get really messy. We can have complete shifts in tropical systems.”

1. What can we infer from the figures listed in para. 1?

A．The problem of marine heat waves is becoming worse.

B．The satellites enable scientists to record ocean temperature precisely.

C．Climate change is the main cause of the marine heat waves.

D．Marine heat waves have been found by scientists for about 30 years.

2. What does the 2nd paragraph mainly talk about?

A．Various factors that lead to marine heat waves.

B．The possible impacts of a warm ocean surface.

C．The possible reason why marine heat waves last long.

D．Scientists’ efforts in exploring the causes of heat waves.

3. What do we know about the impact of the marine heat waves?

A．The impact will disappear shortly after the sea water cools.

B．It takes long before the ecosystem makes a complete recovery.

C．Scientists have known enough to restore the impact.

D．The northeastern Pacific and Western Australia are the worst cases.

4. What is Eric Oliver’s attitude towards the heat waves in tropic waters?

A．Concerned.

B．Indifferent.

C．Doubtful.

D．Optimistic.

2 . In the animal kingdom, parents adopt babies that aren’t their own, and even other species. Why do they do it?

For foster(领养) parents, there are huge costs, with no promise of passing on genes.     1    , because it seems to be wholly altruistic(利他主义的). But this makes it especially confusing in animals, who do not have the cultural influences we do.

One of the most striking places to see adoption in the animal kingdom is AnoNuevo Island, rising from the sea less than one kilometer off the rocky California coast.     2    

From 1976, scientist Marianne Riedman studied adoption among the seals and why it was happening. It’s a crowed beach, with high tides and rough surf, which explains why many little seals each year were separated from their mothers at least once, some permanently.

The researchers counted a total of 572 adopted little seals over the course. Interestingly, some adult seals were likely than others to become foster parents. For one thing, all the foster parents were female.     3     Yet among females, the most common foster seal was a mother who had lost her own child. Why might this be? One possible reason is that adoption helped these females reproduce later on.

Regular nursing may cause them to give ovulation(排卵).     4    

Another possibility is that mothers are prepared to care for their children immediately following birth.     5     the motivation towards care may be so great that they redirect their attention onto other unrelated little animals.

A．Considering the absence of their own young

B．Scientists have long been interested in adoption

C．Once a year, it is home to hundreds of northern elephant seals to give birth

D．Because those poor little seals can meet the seals of their own size in the foster family

E．That’s unsurprising, for what drives these poor little seals to seek out care is the need to nurse

F．In turn it could make a female more likely to give birth to her own child the following season

G．Only in this way can the species go on keeping its unity and power to fight against the danger

3 . Crop circles are patterns(图案) that appear in fields. The pattern is created when certain areas of the crops are pressed down firmly, but others are left as before. The edge is so clean that it looks like it was created with a machine. Even though the stalks(茎) are bent, they are not damaged. Most of the time, the crops continue to grow as normal. Sometimes, the patterns are simple circles. In other instances, they are complex designs consisting of several interconnecting geometric(几何的）shapes.

Most circles are concentrated(集中) in the south of England, primarily in the counties of Hampshire and Wiltshire. But crop circles are not limited to England. They have been discovered in the United States, Canada, Australia, Japan, India and other parts of the world. The season for crop circles runs from April to September, which coincides(同时发生) with the growing season.

Crop circles were mentioned occasionally(偶然地) before the 20th century, but the phenomenon didn't gain attention until 1980, when a farmer in Wiltshire County, England, discovered three circles, each about 18 meters across, in his oat crop. Researchers and the media went to the farm, and the world first began to learn about crop circles. By the 1990s, crop circles had become something of a tourist attraction. Visitors came from around the world to see them. Some farmers even charged for admission to their mysterious attractions.

Researchers have been thinking about the question of crop circles for several decades, but they still haven't come up with a real answer----they don't know why they exist. Possibly the most controversial(有争议的） theory is that crop circles are the work of visitors from other planets. The most scientific theory says crop circles are created by small currents of swirling winds called vortices(旋风). The easiest explanation for crop circles is that they are man-made tricks , created either for fun or to challenge scientists.

1. What do you know about crop circles?

A．The only appear in April.

B．They were first discovered in 1980.

C．The production of the crops falls as result.

D．The crops still grow well though pressed down

2. Crops circles began to gain public attention due to ________.

A．the visits of tourists	B．a farmer' s creation
C．the high admission charge	D．the attention of researchers and the media

3. What is the last paragraph mainly about?

A．How crop circles might be created.

B．When crop circles were created.

C．The relationship between crop circles and aliens.

D．The influence of the earth' s energy on crop circles.

4. What ' s the main purpose of the passage?

A．To attract visitors.	B．To introduce crop circles.
C．To explain who created crop circles.	D．To ask people to protect crop circles.