下列各句中，没有语病的一项是

_______ the calculation is right, scientists can never be sure that they have included all variables and modeled them accurately

New technologies have made ________ possible to turn out new products faster and at a lower cost. [ ]

The old man cancer. His made us very sad.

In order to earn more money for his new car, the young man has to work for three ______ hours in the evening. [ ]