_________ English can be difficult to learn, it is a very useful tool for communication.
Judy didn’t answer . ______ , she turned and walked away.
I was tired _____ listening to classic music. Let’s listen to the pop songs.
At horse races, everyone has already studied the form (类型) of the horse______.
------ What did he want to know, Jim? -------_________ I could finish writing the report.
A huge fire ______ last night and many houses were burnt down.