I have been to Outer Mongolia.

Coitus interruptus is one method of contraception, but it is not completely reliable.

There are many introduced species of plants living in this park.

He engaged in an extravehicular activity from the spaceship.

He is undergoing training for extravehicular activity.

He is a foreigner, but he can speak Japanese fluently.

This book explains in detail about the use of foreign words.

He took action to stir up unnecessary problems, like poking a bush and bringing out a snake.

The problem of the lost generation should be solved by the whole society.

She is good at knitting and knits something new every day.