My grandfather often told me what he had ___ in the expedition.
It was not until 1920 ____ regular radio broadcast began.
It was about 600 years ago ____ the first clock with a face and an hour hand was made.
____ is a fact that English is being accepted as an international language.
If you go to Xi’an, you’ll find the palaces there more magnificent than commonly ____.
I don’t like ____ you speak to her.