1.[C] Attending 动名词作主语
2.[C] so...that (如此...以致于...,引导结果状从)
3.[D] while (表示对比,"而,然而")
4.[D] had been(wish后的宾从用虚拟语气,有then,说明是对过去情况的虚拟,故用过完)
5.原题跟4题完全相同了,我帮你改了一下,把then改成now.
I wish I ____ at the meeting now .
则选:[C] were (对现在情况的虚拟用过去式,be动词的虚拟语气永远用were.)