No secondhand smoke production.
无二手烟的产生。
There is no risk-free level of exposure to secondhand smoke.
没有风险的二手烟含量是不存在的。
The surgeon general says there is no safe level of exposure to secondhand smoke.
外科主治医生说没有对揭漏的被动吸烟的安全级别定论。
The surgeon general says there is no safe level of exposure to secondhand smoke.
外科主治医生说没有对揭漏的被动吸烟的安全级别定论。
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