.I ___ the English conversation yesterday evening.
The villagers have already known _________ we’ll do is to rebuild the bridge.
The development of industry has been ________ gradual process throughout ________ human existence, from stone tools to modern technology.
—What shall we do tonight then?—_______ -whatever you want.
It suddenly occurred to him ________ he had left his keys in the office.
It was a real race ________ time to get the project done. Luckily, we made it.