Fill the blanks with the prepositions by, with, or by means of Sometimes more than one answer is possible.

1. The lumber was transported ____on_____ train.
2. Current can be varied in a circuit ___________ a rheostat.
3. Earthquakes arc usually caused ___________ the movement of the continental plates.
4. The age of the sample was determined ___________ the carbon 14 dating method.
5. Steel surfaces can be protected ___________ a thin coating of machine oil.
6. The colours of aurora borealis are generated ___________ the effect of solar particles on the various atmospheric gases.
7. The primitive cooling earth was darkened for centuries ___________ hot, dense clouds.
8. The direction of growth of a plant is controlled ___________ light (phototropism).
9. The body temperature of a higher mammal is regulated ___________ the hypothalamus.

by, with, or by means of

2. Current can be varied in a circuit __with__ a rheostat.

3. Earthquakes are usually caused __by__ the movement of the continental plates.

4. The age of the sample was determined __by means of__ the carbon 14 dating method.

5. Steel surfaces can be protected __with___ a thin coating of machine oil.

6. The colours of aurora borealis are generated _by__ the effect of solar particles on the various atmospheric gases.

7. The primitive cooling earth was darkened for centuries __by___ hot, dense clouds.

8. The direction of growth of a plant is controlled __by___ light (phototropism).

9. The body temperature of a higher mammal is regulated __by__ the hypothalamus.