_____ crying sadly, he raised his head and let tears stream down his face on purpose. [ ]

14．This doubt had been in my mind for some time, but the research still went on____some reasons

He _____ articles for our wall-newspaper these three years, and he _____ about forty articles

The professor held the crucible the Bunsen flame when heating the substance.

“Who Moved My Cheese?”, ____________ is a best-selling book, is written by Spencer Johnson.