It’s ten years since the scientist ____ on his life’s work of discovering the valuable chemical.

Traditionally, Chinese people _________ the Chinese characters Double Happiness and stick them onto walls or doors for weddings. 

---I regret _____you John has been fired .---I can hardly believe my ears .He is such a fine worker .

—Alice, you are going shopping this afternoon, aren't you? Anything special in your mind?—Nothing       ________. I just haven't done shopping for a long time.

---Tom, keep your_____ on your studies. --- Sure, mum. I'll keep that in_____.