It is dark outside, so please____ your step while going down the stairs.

The sports meet, originally____ be held lastFriday, was finally delayed because of the bad weather.

下列各句中，加横线词的活用现象与其他三项不同的一项是（ ）

What’s that— _____is a jacket.

For a long time they walked without saying____ word. Jim was the first to break ____ silence.