Present simple vs continuous

Private airlines (take / are taking) the place of national airlines.

• take

• are taking

Recent research (shows / shows) that trees belong to a type of social network.

• shows

• are showing

People who are not comfortable with technology (do not understand / are not understanding) the instructions on the software.

• do not understand

• are not understanding

Tourists (visit / are visiting) Hong Kong in record numbers these days.

• visit

• are visiting

If the sample size of an experiment is too small, the size (ruins / is ruining) the results.

• ruins

• is ruining

Environmental scientists are concerned because icebergs (melt / are melting) at a very rapid rate.

• melt

• are melting

Teachers report that the new arts education program (improves / is improving) students' critical thinking skills.

• improves

• is improving

According to some sociologists, pure democracy (does not exist / is not existing) in the world today.

• does not exist

• is not existing