1, Finish your homework or you can't go out with your friend (if)
\(\rightarrow\)..............................................................
2, They're not sure how they should operate the new system (to)
\(\rightarrow\)...............................................................
3, It took me 4 hours to read the first chapter of the book (spent)
\(\rightarrow\)................................................................
4, Snowboarding is more dangerous than tennis ( as )
\(\rightarrow\)....................................................................
1, Finish your homework or you can't go out with your friend (if)
→→If you don't finish your homework, you can't go out with your friend.
2, They're not sure how they should operate the new system (to)
→→They're not sure how to operate the new system.
3, It took me 4 hours to read the first chapter of the book (spent)
→→I spent 4 hours reading the first chapter of the book.
4, Snowboarding is more dangerous than tennis ( as )
→→Tennis isn't as dangerous as snowboarding.
1, Finish your homework or you can't go out with your friend (if)
→→.........If you don't Finish your homework , you can't go out with your friend ..............
2, They're not sure how they should operate the new system (to)
→→........They're not sure how to operate the new system................
3, It took me 4 hours to read the first chapter of the book (spent)
→→.........I spent 4 hours reading the first chapter of the book............
4, Snowboarding is more dangerous than tennis ( as )
→→.............Tennis isn't as dangerous as Snowboarding .....................