A '$pioneer^{\prime} is a/an :$

1.According to some studies, dolphins, whales and ¾ other sea creatures use highly sophisticated navigation systems.

2.We have to do some research in order to ¾ the possible factors that could affect the outcome of the project.

3.Many people who live near nuclear plants are concerned. __ go wrong, the impact on the surrounding area could be disastrous.

4.Supposedly, digital versatile disks, or DVD as they are called, are __ resistant \to scratching __ records.

5.The government __ that the projects __ with great success.

6.These differences between the two photographs __ with the help of computer programs.

7.The skill of safe driving __ necessary $\to avoid$ collisions, which __ many thousands of people annually.

8.Salma could not tell __ books were \left on the table.

9.They like \to keep their old houses rather than build new ones __ it is very difficult and expensive \to maintain them.

10.Hydrogen peroxide __ as a bleaching agent because it effectively whitens a variety of fibres and surfaces.

11.__ can be grown on arid land.

12.There are three kinds of solar eclipses : one is total, another is annular, and __ .