Using “be” in sentences

There (is /are) five types of computers: laptops, desktops, servers, mainframes, and supercomputers.

• is

• are

Some research suggests that drinking bottled water (is / are) bad for your health.

• is

• are

The production of meat (is / are) one of the main contributors to climate change.

• is

• are

In the year 1800, the world population (was / were) 1 billion.

• was

• were

Mining and farming (is / are) two of the main causes of water pollution.

• is

• are

One responsibility of a chief executive officer (CEO) (is / are) to develop the company's long-term plan.

• is

• are

At 116 years old, Susannah Mushatt Jones (was / were) the world's oldest living person in 2015.

• was

• were

There (was / were) over 7.5 million cars in the United States by 1920.

• was

• were

Overfishing (a)   catching so many fish that they cannot replace themselves. Overfishing means we have fewer fish to eat.

It (a)   also harmful to other plants and animals in the ocean.