Beijing, the capital of China, is one of__________ cities in the world.

Your father’s never been to other countries, _________ he— ________. He plans to go abroad for a second time.

Was it in the train “ Harmony”, ______ is China’s first high-speed one, that John met with his foreign friend？

gh the huge engine, as tallas 25 meters, is heavy_______, it is powerful and works well.

This is _______ important book. It helped me a lot in ________ old days.