`6.` karthik can play the piano but he can't play the violin

`=>` S + can + Vinf + O

`7.` She is hard working but her brother is very lazy

`=>` S + tobe + adj but S + tobe + adj

`8.` She is beautiful and clever

`=>` S + tobe + adj and adj

`9.` You can take the blue shirt or the green shirt

`=>` S + can + Vinf + O

`10.` My sister is tall but i am short

`=>` S + tobe + adj but S + tobe + adj

6. Karthik can play the piano but he can't play the violin.

-> S+Vo+O

7. She is hard working but her brother is very lazy

-> S+tobe+adj

8. She is beautiful and clever.

-> S+tobe+adj

9. You can take the blue shirt or the green shirt.

-> S+can+Vo

10. My sister is tall but i am short.

-> S+tobe+adj...but...S+tobe+adj