Write the verb in brackets in the correct form. The United Nations has meetings where world leaders agree on what to do about global warming. If there is too much pollution in the air, some people (to have) health problems.
The United Nations has meetings where world leaders agree on what to do about global warming. If there is too much pollution in the air, some people will have health problems.
The United Nations has meetings where world leaders agree on what to do about global warming. If there is too much pollution in the air, some people will have health problems.