There are two forms for the Imperfect Subjunctive in Spanish. The -se form is considered the traditional form of the imperfect subjunctive, while the -ra is derived from an old Latin indicative form. Both are almost interchangeable in modern Spanish... So yes.
1. Si es la calculadora de Adela
2. Si es su clase de español
3. Si son los papeles de la profesora
4. Si es de ella
5. Si es mi novia
6. Si son los lápices de nosotros
