Hoàn thành các câu sau :
1 ) He is lazy. He gets bad marks . ( Combine these sentences with " if " )
2 ) We make the air dirty. We use the car all the time ( Combine these sentences with " if " )
3 ) the / Sydney / city / is / cleanest / world / in / the ( Rearrange the words to make a sentence )
4 ) If / plant trees / school yard, / school / greener place. ( Make sentence using the words given )