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 ______catching so many fish that they cannot replace themselves. Overfishing means we have fewer fish to eat.

It_____ also harmful to other plants and animals in the ocean.