.If a computer crashes, you will lose the file you _________unless you save it regularly.
.It was in the 1990s _______ we were working together ____ we made friends with each other.
—Tom, help me buy two tickets for this weekend’s concert online.—Sorry, there is no ticket _______ online now.
Anti-Japanese War _______ in 1937 and it _______ eight years
---Do you know what WWF______ ?----Yes. That’s World Wide Fund for Nature.
In developed countries, farm workers _________ only a small section of the population.