Though it is the first time they have met, they talked as if they _____ friends for many years.

—The research on the new bird flu virus vaccine is challenging and demanding. Who do you think can do the job?—____ my students have a try?

I would have come to see you earlier, but I __________ too busy.

——I can’t find my purse anywhere.——You       have lost it while shopping.

How I wish I ________ in medicine instead of history when I was at college!