1. (2021九上·温州开学考) 语法填空

Many people know that rubbish is a big problem on planet Earth., many people don't know that rubbish is a problem in outer space too.

According to BBC News, there are more than twenty (thousand) prices of space rubbish around the earth. They move around the planet at a high spaced. But even a very small piece can break important satellites or become (danger) to astronauts.

(make) less space rubbish, countries have agreed that all new space tools can only stay in space for 25 years at most. Each tool must be built to fall (safe) into the earth's atmosphere after that time. In the upper parts of the atmosphere, it will burn up.

Many scientists also suggest different ways on to clean up space rubbish. The (German) are building robots that can collect pieces of space rubbish and finally bring them back to Earth.

"The situation (become) more serious since we sent more objects into space to help people use their mobile phones and computers," says Marco Castronuovo, Italian space researcher.

"It's time to do something. The (early) we start to solve the problem, the better," he says.