Rewrite the sentences

1. Tom couldn‟t go to school because he was very poor.  Because of ..............................................................................................................................
2. I can‟t buy this bike because I don‟t have enough money.  Because of ..............................................................................................................................
3. He failed the exam because he didn‟t learn the lesson carefully.  Because of ..............................................................................................................................
4. I went to bed early because I felt tired.  Because of ..............................................................................................................................
5. Because Tom didn‟t have high salary, he worked so hard.  Because ................................................................................................................................