`1`.Although Nam was tired , he stayed up late to finish his homework

`\rightarrow` Although + C1 + C2 : Mặc dù

`2`.The festival which I joined in last week was wonderful

`\rightarrow` Which là ĐTQH dùng để thay thế DT chỉ vật làm chủ ngữ

`3`.Bill Gates , who is the president of Microsoft company , is a billonaire

`\rightarrow` Who là ĐTQH dùng để thay thế DT chỉ người làm chủ ngữ

`4`.The roses which my dad gave my mom on her birthday were very sweet and beautiful

`\rightarrow` Which là ĐTQH dùng để thay thế DT chỉ vật làm chủ ngữ

`5`.If we don't hurry up , we will miss the train

`\rightarrow` CĐK Loại 1 :

`-` If - clause : Thì HTĐ : S + Vs / es / không s , es

`-` Main - clause : Thì TLĐ : S + will + V

`\text{@ TheFox}`