_____________ is necessary __________ he trains himself before the Guangzhou Marathon.
—Where is Gary? —He _______ in the library.
Lily and Grace are my best friends. ________ of them are very smart.
—________ I use your pen? — Sure. Here you are.
—________ are we going to meet? — In front of the shopping center.
The beach is not as ________ as it used to be. Let’s collect the rubbish.