Changing the design of a new product may ____ the riskof its production in the market

How do you keep in touch with your old classmates or schoolmates? -By chatting with them on the Internet, _______for three hours every day [ ]

The nurse allowed the visitors to remain the visiting hours，though it was not permitted.

In English class, our teacher often creates an environment __________ we are given the opportunity to solve problems ourselves.

set doesn’twork, the water tap is dripping and my car is still under repair!–You sure________ bad luck these days