We decided to travel by land.

We went over the mountain by land.

He continued his strenuous efforts to pass the exam.

He made strenuous efforts to pass the exam.

This medicine has a delayed effect, so you may not feel the effect immediately.

His project reflects his ingenuity.

It is important for men to regularly clean smegma.

The treatment efficacy of this medicine is very high.

I'm always impressed by his skillful handiwork.

Geologists believe that this area was formed by a graben.