B: During the first days of the Spring Festival holiday, pollution levels aren't ____ ____ ____ they were last year.
长方体ABCD﹣A1B1C1D1中,AB=BC=3,AA1=6,则异面直线BD1与CC1所成的角等于( )
“SARS”病毒的遗传物质中含有核苷酸的种类及碱基的种类分别是( )
“你希望别人怎样对待你,你就应该怎样对待别人。”这句话说明在与异性交往的过程中( )