For questions 17 - 24, read the text below. Use the word given in capitals at the end of some of the lines to form a word that fits in the gap in the same line. 

Eating in space

Over the years, space (0) EXPLORATION (EXPLORE) has had a huge amount of investment and involved many people. All of this has been

(17) (BENEFIT)  to society; without it we wouldn't have such devices as mobile phones or satellite TV today. There have been countless

(18) (DEVELOP)   in many aspects of space travel but advances made to food consumed in space have been (19) (RELATE)  slow.

Most early suggestions for the (20) (PROVIDE)  of food for astronauts were unacceptable, for example shredding their printed mission instructions and sprinkling them with water enriched with vitamins. The freeze-dried foods they did initially consume would doubtlessly have been regarded as totally (21) (EDIBLE)   by those of us on Earth.

Today the (22) (INHABIT)  of the International Space Station fortunately have a more appetising diet, since the larger spacecraft which is now being used (23) (ABLE)  them to take tinned foods and flexible pouches containing meat and vegetables. However, despite this, their food still remains limited, due to the (24) (GO)  challenges encountered with lack of gravity and the necessity for food to be sterile.