Sandstorms in Asia seem _____ in recent years as a result of desertification.

He sent me an e-mail,       to get further information.

Which do you enjoy___your summer holiday,taking a part-time job or staying at home?

The police at Denver International Airport examined a bomb threat against a United Airlines flight to San Francisco,____________ the flight for hours.

I remembered _____ the door before I left the office, but forgot to turn off the lights.

I was told that the stadium was well worth ___.

The ______ addicted to ______ computer games made his mother worried.

Unluckily, my sister had her cellphone ______ in Guangzhou before she could find a job.

The bell __ the end of the period rang, __our heated discussion.

________ the programme, they have to stay there for another two weeks.
A Not completing            B Not completed  
C Not having completed      D Having not completed