We have realised that ____ is much that can be done to help improve our environment.

All of us have the desire to visit the three main temples in Athens, especially ______ that contains a gold and ivory statue of Athena.

I am afraid there’s __________with the computer. Can you come and have a look?

—What can I do for you?—I’d like to buy a computer for my son, ______ at a good price but of great quality．

Here are two pairs of shoes, ______ you may choose.