is of no importance to great thoughts, ________ are as fresh today as when they first passed through their authors’ minds, ages ago.

trials, people are ________assigned to a “treatment” group, which benefits from the project, and a “control” group, which does not.

She didn’t answer the phone.She ___ be asleep.

As ________ , they were waiting for us at the airport.

The blue shirt ______ sixty yuan, and the shorts ______ twenty yuan.