A．Early detection should be attached much importance to.
B．It's unrealistic to prevent people from cancer.
C．More resources should be put in the treatment of cancer.
D．All types of cancers can be cured at their early stages.
A．They help employers contact the employees.
B．They save employees' money on gadgets.
C．They allow employees' family to enjoy the equipment.
D．They reduce employees' total working hours.
A．The previous surveys．
B．Experiments．
C．Employees' complaints.
D．Researchers' observations.