The local Tibetans and Sherpas laughed at the strange bottles containing ________ they referred to as “English air”

Before Tom left home, his mother kept telling him to ________ his manners at the party.[ ]

To learn English well, you should ______ as many words and expressions as possible.

What do you think of the room — It’s too dirty .

The boy was last seennear the West Lake.[ ]