In the past half-century, average incomes _______ quickly in developed countries, yet happiness levels have remained almost the same.

Walmart, which is one of the largest American supermarket chains, _______ some of its store open 24 hours on Mondays through Saturdays.

She insisted that we ________ the source of the river and begin our journey there.

--- I haven’t seen Mary recently. And you?--- Me neither. I’m afraid she _________ to her experiment for too long a time.

The news came as no surprise to me . I ____ for some time that the factory was going to shut down .