题目选项分析

The use of the battery-powered devices known as e-cigarettes may lessen smoking rates, but without adverse side effects or increased addiction demonstrated, it should not be recommended as a substitute for tobacco cigarettes.

The use of the battery-powered devices known as e-cigarettes may lessen smoking rates, but until it has been demonstrated neither to have adverse side effects nor to increase tobacco addiction, it should not be recommended as a substitute for tobacco cigarettes.