enigmas

"to present an envoy to the king"

"Archaeologists carefully dig in the dirt, looking for clues about past civilizations. "

"My friend told me there was something in the box, but I didn't know what it was yet. "

"After the party, only a few close friends remained to help clean up. "

"The sudden, inexplicable silence in the classroom before the test made everyone nervous. "

"He received a mysterious phone call this morning."

"Professor Smith, the head of the history department, gave a fascinating lecture on the Roman Empire. "

"Scientists develop theories to explain how the universe works. "

"The ancient Egyptians used hieroglyphs, which are picture-like symbols, to write on temple walls. "

"The sudden disappearance of my keys is really puzzling me. "

"The complicated instructions on the new software difficult me from completing the project on time. "

"a mathematical problem"