Definition think in British English

The verb think is rarely used with an infinitive. Don’t say ‘think to do something’.

When think means ‘to consider facts in order to understand something or make a decision’, it is often used in the -ing form and in the following structures:

▪ think of doing something

▪ think about doing something

✗ Britain changed its policy and many countries are thinking to do the same.

✓ Britain changed its policy and many countries are thinking of doing the same.

✓ Britain changed its policy and many countries are thinking about doing the same.

✗ Researchers should think to use methods that don’t require animal testing.

✓ Researchers should think of using methods that don’t require animal testing.

✓ Researchers should think about using methods that don’t require animal testing.

When think means ‘to believe’, the usual structure is a that-clause:

✗ A lot of people think to have more sex appeal if they drive a powerful speedy car.

✓ A lot of people think (that) they have more sex appeal if they drive a powerful speedy car.

However, the infinitive can be used in this meaning, but only in the passive structure be thought to do something:

Many secret organizations are thought to be at work in the country.