She loves giving parties, and does so whenever she can find_______.
Thousands of foreigners were______ to the Shanghai World Expo the day it opened.
My father made me a promise ___ he would buy me a present if I got a good mark
I have finished translating a large part of the book, but the rest ___ more difficult.
After the new type of rice was introduced, the farmers produced _______ rice this year as last year.
The chairman thought _____ necessary to invite Professor Smith to speak at the meeting.