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.

It’s my great honor to have the opportunity to call on all of you to take part in volunteer activities     1    .

In my view, firstly, volunteering can     2     both mental and physical health for a volunteer. An individual who volunteers may see a rise in their     3     because helping others can provide a sense of achievement.     4    , no one can deny the fact the volunteering enables us to build     5     skills.

Volunteering can not only make us feel good but also makes our world more     6    . So, join us!

Thank you!

The greatest     1     began the night before Spring Festival. Fireworks were being let off across the city, suddenly lighting up the night sky. Children were covering their ears but with an expectant look on their faces. Mrs Chen said that it was to     2     the monster Nian. The fireworks were a lot of fun! We then sat together to enjoy a big dinner,     3     everyone a happy new year.

When people started creating their own avatars, they discovered that they were going to have the power to create new identities that did not look or act like their real selves at all. They could dress their avatars infancy clothes, or they could try being someone of the opposite sex, and call themselves “Andy” instead of “Anna”! When Internet users realised that their avatars would     4     by many people, not just their friends, they started having more than on avatar: a sensible one for work; a friendly, good-looking one for meeting people; and a silly one for having fun. Avatars let you express yourself and give you lots of room for     5    .

Firstly,     6     online is no replacement for face-to-face contact — images really cannot replace a real-life smile or hug. According to a parenting expert, Denise Daniels, communicating through a screen makes     7     more difficult for children to concentrate or show kindness to others. As we know, important social skills are developed through direct contact with other people. It is these skills that enable us     8     lifelong friendships.

Thirdly, online relationships may not be what they appear to be. Friendships are built on the basis of trust, and with online communication you can never be 100 percent sure that the people you are chatting to are being honest about     9     they are. Because of this, going online can be particularly     10     for people who are easily influenced or too trusting.

Besides such ethical concerns, the legal situations the autonomous vehicle industry is likely to be confronted with have     1     heated debates. In this emerging industry, manufacturing and programming standards are not yet     2    . Moreover, the quality and safety of the technology used in self-driving cars is still being challenged. This could lead to extraordinary cases like who should be held     3     when self-driving cars are involved in accidents — should it be the driver, the software programmer or the manufacturer? Manufacturing and programming standards first have to be agreed upon to make it possible for law courts to decide who is at fault when things go wrong. As     4     in autonomous vehicle design and technology are in progress, the final agreement on laws and regulations     5     this industry remains to be seen.

We often hear of people talking about Karaoke. But what on earth it is about, it r    1    a question for many people. Karaoke is a sort of acoustic (音响的) equipment     2    was invented in Japan around the middle of the 1970’s. It means “a band without people”    3    Japanese. In     4    , it is just a music tape without words. This equipment first appeared in some     5    (公共的) houses and snack bars, and mainly for the     6    (顾客) to enjoy themselves. Most of the music in Karaoke was popular music.

Shortly after its invention, Karaoke was s    7     to the whole world. It was     8    (引进) to China and was welcomed by many people. A    9     you are not a good singer, or even sometimes you may sing out of tune, you can always enjoy     10    by singing Karaoke.