While he was in Beijing, he spent all his time ()some important museums and buildings.

单项选择题Please () from smoking until the aeroplane is airborne.

A．refrain
B．prevent
C．resist
D．restrain

单项选择题Since the early nineties, the trend in most businesses has been toward on-demand, always-available products and services that suit the customer's ()rather than the company's.

A．benefit
B．availability
C．suitability
D．convenience