t because of his laziness_______ he didn’t dothe experiment successfully- No, it was because of his carelessness.

－My parents always warns me ______ with fire.－They are right. It’s dangerous.

The police still haven’t found the lost child，but they’re doing all they ________．[ ]

When will you hand in your homework—Sorry, I’m not sure. I _______writing it yet.

The boy wanted to ride his bicycle in the street, buthis mother told him_________.