The teacher wouldn't be disappointed if I were not lazy like this ( not be/ not be).
I shouldn't have believed it if I hadn't seen with my own eyes ( not see).
If you had arrived ten minutes earlier, you would have got a seat ( arrive/ get).
If you had spoken more slowly, they might have understood you ( speak/understand).
If he had read the instructions carefully, he would have washed in hot water (read/ wash).