He made strenuous efforts to pass the exam.

We went over the mountain by land.

He continued his 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.

Geologists believe that this area was formed by a graben.

The treatment efficacy of this medicine is very high.

I'm always impressed by his skillful handiwork.

He dug a hole in the ground and stored vegetables.