When asked why he went there, he said he was sent there ________ for a space flight.
. The 2010 Shanghai World Expo is well worth ______.
I am interested in traveling. It is ______ but ______.
The windows haven’t cleaned for a long time. They need ______.
Our teachers are really ______. They often work in their office far into the night.
Visitors were at the pictures that the guide showed.