Choose the correct words to complete the sentences

 Exercise 2: Choose the correct words to complete the sentences.
completely          
reach                    
among           
view                 
observe
size
discover
necessary          
invent
reflect
1. Researchers often " ? " animals in order to learn about their behavior.
2.A spacesuit is "?" when astronauts walk in space.
3.Scientists look for planets that are close in " ? " to Earth.
4. You should wear white in the summer. White clothes " ? " he heat from the sun.
5. I found your sweater " ? " my winter clothes.
6.He wants to "?" a new kind of telescope.
7.From this spot on the mountain, we can "?" the entire valley.
8. Much of the Artic was "?" covered by ice, but now there are places of open sea.
9. To "?" the top shelf, I have to stand on a ladder.
10. When did they "?" Saturn’s moons?