下列各句中，表达得体的一句是 （    ）

_____ can you get a better job in so competitive working places.

Now more people are paying attention to the school bus safety.–So we believe ______ there will be fewer accidents in the future.

Is Tom still smoking?—No．By next Saturday he _____________ for a whole month without smoking a single cigarette

He became inspired when he thought about helping ordinary people ________ to cholera.