`2`.We can't swim in this river because it is so dirty

`\rightarrow` Because + C1 + C2 : Bởi vì ( `2 , 10` )

`\rightarrow` Dùng để chỉ nguyên nhân , lý do ( `2 , 10` )

`3`.If you work hard , you will pass the exam

`\rightarrow` CĐK Loại `1` : Diễn tả hành động có thật ở Hiện tại ( `3 , 6 , 9` )

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

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

`4`.My brother plays tennis very well

`\rightarrow` Thì HTĐ : S + Vs / es

`\rightarrow` Đi sau ĐT là `1` Trạng từ

`\rightarrow` good ( adj ) `->` well ( adv ) : tốt

`5`.Since I'll be on vacation next week , I won't be able to attend the meeting

`\rightarrow` Since + C1 + C2 : Bởi vì

`\rightarrow` Dùng để chỉ nguyên nhân , lý do

`6`.Unless you start working hard now , you won't be able to pass the final test

`\rightarrow` Unless `=` If not : Trừ phi ( `6 , 9` )

`7`.They have played football for an hour

`\rightarrow` Thì HTHT : S + have / has + VpII

`\rightarrow` For + Khoảng thời gian : Bao lâu

`8`.What about using public buses instead of motorbikes ?

`\rightarrow` What about + V-ing ? : Hỏi ý kiến

`9`.Unless you succeed , you will have to try it again

`10`.Because it is a national holiday , you won't find many shops open

`\text{#nguyenngoctamana}`