因为环境变化很快所以在动态的户外环境中测量二手烟是困难的。

it's hard to measure smoke dynamics outdoors because conditions change rapidly;

youdao

因为环境变化很快所以在动态的户外环境中测量二手烟是困难的。

it's hard to measure smoke dynamics outdoors because conditions change rapidly;

youdao