Are Jim and Bob playing outside—-_______.They are doing their homework in thestudy.

It was not until the supreme lending crisis (次贷危机)had caused great damage to the American financial system ______ Americans realized the severity (严重性) of the situation. [ ]

Will you buy this T-shirt for Mum— I have no idea. I don’t know______ or not the colour matches her jeans.

He is really like a gentleman and he usually thedoor open to let the ladies go first

Look, Mary has a new bike. How nice it is !—Yes. Her parents bought _____ for her progress in this exam. My parents also bought _____ for me for my improvement in English.