Come and see me whenever________.
It was not until 1938 _________ the first colour TV programme was broadcast.
Mr. John was so humorous that we had a good laugh ______ the meal.
I don’t think it easy, even if we work hard, ______ the South Korea and the North Korea to sit down to talk at present.
No student ______ go out of the school campus after 10:00 at night without permission according to the school regulations.
“Ungelivable” is so new an English word coined on the Internet ______ is forbidden to appear in official media or documents at present.