Which of these human activities in a forest has a positive effect on the ecosystem?
A: Planting new trees where old ones were cut down

Which SI unit would be most appropriate for recording the length of a typical classroom?
A: meter

According to the periodic table, all of the following are metals except
A: fluorine

A teacher places an item in a box. The item takes the shape of the entire container. This item is most likely
A:
air.