Ответ:
I
1. If he learned the poem, he would not get a bad mark.
2. If Barbara got up at half past eight, she would be late for school.
3. If he warned me, i would do the work in time.
4. If he worked hard, he would achieve great success.
5. If she did not help you, i would be in a very difficult situation.
II.
1. If i were you, i would do it now.
2. If Boris visited me, i would lend him my tools.
3. If Masha helped in the kitchen, she would get more pocket money.
4. If you had told me about this situations, i would have helped you.
5. If i had known about it, i would have been happy.