Ability with Can and Could

For example, a new road in Italy ___ “eat” pollution and clean the air.

We ___ also build new roads out of recycled materials.

However, now scientists ___ make new, long-lasting roads.

In the past, many roads ____ last very long.

In the past, engineers ___ make roads that were environmentally friendly.

In the United States, we ___ build new roads that collect heat from sunshine. The heat keeps buildings warm.

About 100 years ago, drivers ___ imagine these changes were possible.

In the twentieth century, heavy traffic and bad weather ___ damage roads.

These new roads ___ last a long time without repairs.

Now we have roads that ___ protect the environment.