方程x2﹣9x+18=0的两个根是等腰三角形的底和腰，则这个三角形的周长为[ ]

用化学用语表示：

①磷元素________；②空气中含量最多的气体________；③3个铝离子________；④葡萄糖__________。

He did behave himself admirably in the interview, but in considering applicants for the position, we

give preference to          with rich experience.[ ]

A. those

B. that

C. any

D. ones

Do you enjoy _______ football? I hear there will be a football match tomorrow.

A．playing

B．play

C．played

D．to play

我国现行税法规定，对进口应税产品不征收资源税，相应地对出口应税产品也不免征或退还已纳资源税。（）

08-32捣固车线路方向偏差检测装置由四台检测小车、一根钢弦、（）及相应仪表组成。