关于二极管的开关作用，下列说法正确的是（ ）。

are claimed to make smoking to some extent safer, but they can only marginally reduce, not eliminate the hazards.7. What conclusion can we draw after reading this article？A．The effect of cigarette smoking on health is not so much．B．Smokers would often die from lung cancer．C．We should not neglect the bad influence of smoking, so don’t smoke or don’ t start to．D．More and more physicians and research workers are less sure of the effect of cigarette smoking on health．

ies conducted during the 1970s on prents-children reltionship indicted tht ______.dolescence did not cuses much troubles clinicinsnd theorists hd stted B．children’sggressivenessnd rebelliousness were growing C．children-prents reltionship ws declining D．teengers becme even morebhorrent of their prentsA．adolescence did not cause as much trouble as clinicians and theorists had statedB．children’s aggressiveness and rebelliousness were growingC．children-parents relationship was decliningD．teenagers became even more abhorrent of their parents