With the quick spread of COVID-19, more and more people around us are tested p    1    and people grow more and more     2    (焦虑). Here are some effective measures to p    3    you from being infected(感染)with the virus.

First, wear masks wherever you go, though it is not c    4    for you to perform daily routine. Second, m     5    distance from others. It is of extreme importance to avoid direct c    6    with those who have fever, cough or other COVID-19 symptoms(症状). Third, eat properly to ensure you have enough     7    (营养). If you have to eat outside, bringing food from home is     8    (推荐). Last but not least, we should a    9    importance to rest and exercise, which can help you     10    (恢复)sooner if you should fall ill.

No matter how exciting space exploration sounds, there’s an important point that needs to be considered: food supplies. Right now, astronauts typically       1     (依赖) dry food in airtight bags and cans, since there are strict weight limits on items taken into space. Foods that we     2     (认为是理所当然的), such as fresh fruit and vegetables, are out of the question for space explorers.

For those who     3     (有强烈的愿望) to grow food during space flights, they’ve faced many difficulties, including the absence of gravity, and a lack of soil, air and humidity (湿度). However, growing food to add and minimize the food that must be carried to space will be increasingly important on long-duration flights into space. Recently, a leading team has worked out how plants can absorb nutrients from human urine (尿). Human urine is 95 percent water, with the other 5 percent    4     (构成；组成) nutrients which are harmful to the human body but not to plants, and it could supply three to four out of the six nutrients that plants need. By recycling liquid waste and producing food, an efficient cycle will be created.

And most importantly, the duration of space flights will be greatly extended to “20 years of flight”, meaning we may be soon sending astronauts on flights to Mars, or even beyond.

Artificial intelligence aims to create intelligent machines. To achieve the aim, many approaches to     1    (create) true AI have been put forward. The dream of AI     2    has been around for centuries has finally become a reality. Nowadays, AI is already being applied in many fields. From autonomous vehicles to domestic robots, from     3    (recommend) systems to computers writing novels, AI has     4    unlimited number of applications. The technology     5    (transform) the way we live. However, the question is, where will all this lead?    6    we become more and more dependent on computers, some scientists are urging us to think about the dangers     7    (pose) by the advances in AI. Stephen Hawking, for example,    8    (warn), “The development of full artificial intelligence could spell the end of the human race.”     9    (apparent), such warnings demand our attention. We need to make sure that we will not fall victim     10    AI.

For most people before the mid-20th century, it was impossible to travel into space. However, it was some scientists’     1     to help humans to fulfill their dream of     2     space. With many experiments done, they had rockets made successfully, which could escape Earth’s     3    . Then on 4 October 1957, the Sputnik 1 satellite was launched by the USSR and     4    orbited around Earth. Some time after that, the USSR     5     on sending people into space, and on 12 April 1961, Yuri Gagarin became the first person in the world to go into space. Over eight years later, on 20 July 1969, American     6     Neil Armstrong said, “That’s one small step for a man, one giant     7     for mankind.” when he stepped on the moon. Following Russia and the US, China was the third country to send humans into space on its own in the Shenzhou 5     8     in 2003 when Yang Liwei successfully     9     Earth, which was a main     10     for China.

Are we a    1    ? What’s out there ?” Looking up at the s    2     , people have always wanted to l    3    more about space , and scientists work h     4    to find answers . They m    5     vehicles to carry b     6     people into space to find out the s    7     of the universe.They also really wish to d    8     other planets that are s    9    enough to s    10     life .

Astronauts’     1     in space is quite different from that on the Earth.

Astronauts usually sleep in     2     and attach themselves to avoid floating around. Astronauts’ main task inside the space station is to conduct     3    . And the most challenging work outside the space station includes     4    , monitoring scientific experiments or repairing the space station, so     5     is necessary. Astronauts eat dried or     6     food, drink through a     7     of plastic and ensure a balanced nutrients by taking pills. Astronauts have to do at least two hours of     8     in space every day because     9     has great bad effects on their body. Astronauts like     10     of the Earth in their leisure time.