unterstreichen in English:

underscore a common concern about the GDP by citing a critic.

The errors underscore tensions that are heightened by North Korea’s nuclear program, and a debate over how best to confront it, including today at a U.S.-Canadian summit.

Please, underline verbs.

There is so far no indication that any Poles were among the victims of the Paris terrorist attacks, the spokesperson of the Foreign Ministry, Marcin Wojciechowski underlines.

You should underline the crucial characteristics of the products.