IV. Supply the correct form of the words in brackets.

1. The smartphone is one of the most useful ………………………………. devices.            (wire)

2. Solar panels take energy from the sun to produce …………………………….                                                   (electric)

3. Household waste ……………………………the environment when not disposed of properly. (pollution)

4. More and more companies are making products from ……………………………materials.                              (recycle)