His actions obstructed our plans.

His actions are obstructing our plans.

He dedicated his life to education.

He suffered a serious injury during a soccer match.

He injured his arm in an accident.

This area has been hit by major disasters many times in the past.

This year is the year of the 24th of the sexagenary cycle.

This chemical is harmful.

This chemical is harmful and has a negative impact on the environment.

He spends a lot of time on research activities outside the school.