How often do the students play sports?

The professor could tell by the _______look in Maris’s eyes that she didn’t understand a single word of his lecture

When asked about their opinions about the schoolmaster, many teachers would prefer to see him step aside ________ younger men.[ ]

eople have been ill with a strange disease these days,____we’d never heard of before.

Mr. Li will go to Guangzhou by air. His workmates are ______ him off at the airport.