My grandfather is seventy years old.

I will explain this matter in detail in the future.

He is majoring in geology at university.

He participated in the anti-Japanese movement.

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.