I used to drink a lot of tea but these days I _____ coffee

The guard at the entrance didn’t ______ me in though I had begged him many times.[ ]

China should become a global leader in energy efficiency by 2050________nuclear power is likely to account for at least half of the country’s energy.[ ]

all, reputation is a treasure ________ once lost, can never be won back.

Susan started to clean the room；Lily was preparing lunch