He did all he could _____ .
I’d like to go ________ to help people, ________ when they are in trouble.
The farm grows various kinds of crops, _______ wheat, corn, cotton and rice.
The general said to the men, “Don’t stop practicing. The general _______ the man ________.
The place was flooded ________ it had been raining for several weeks.
In China, those who want to enter universities have to _______ the entrance exams in June.