Everyone here will thank the firefighter for thethings they have done to prevent fires______ the environment safer.

Excuse me, could you tell me how I can learn German well—_____ having conversations with Germans.

I don’t know if he’ll be home tonight or not, you’ll just have to ____.

oted himself ________ to his researchwork, having no time to play.

Was ______ Bill, ______ played basketball very well, ______ helped the blind man cross the road?—Yes, of course. He is always ready to help others.