Choose only the correct form

1. The book was so boring [because|so|in order to] I couldn't read it.
2. The singer sang such a bad song [in order to|that so|as a result] people left the concert hall.
3. I didn't have enough money [so|as|due to] I couldn't buy this dress.
4. Today we had so much work [since|to|that] we didn't have lunch.
5. The last summer day was [that|so|to] rainy [since|to|that] we couldn't go outside.
6. They have [such|so|many] few friends in a town [since|to|that] they can't gather together.