Помогите:
IV. Put the verbs in the right form and then paraphrase the underlined words.

1. The shortage of stone and timber (to lead) in the very early days to the introduction of brick construction.
2. The raw materials (to include) such material as limestone.
3. At the beginning of the construction of the building we should (to plan) properly.
4. It (to be) not easy to create something new in the sphere of science.
5. (To be) it combined with this mixture?
6. I (to be) going to gather pictures of fine architectural buildings