A party ( )in our classroom,we are busy decorating it with c

we are busy decorating it with colored papers and balloons.（我们都忙着装饰彩纸和气球.)就是说,我们都已经想好了要举办一个派对了,现在在安排了.如果用will be held就是说,我们还在想着,筹划着,就是还没有装饰彩纸和气球那些的.结合后半句,那么故而是填is held而不是will be held