she was busy , so she couldn't join us => because

Cách làm:
- Sử dụng từ "because" để kết nối câu, biến đổi câu để có ý nghĩa tương tự.

Câu trả lời:
- She couldn't join us because she was busy.

Being busy, she couldn't join us.

Due to being busy, she couldn't join us.

Since she was busy, she couldn't join us.

She couldn't join us because she was busy.