Coordinating conjunctions

The rain clouds can be seen in the distance, but no has fallen.

• Correct

• Incorrect

They are trying to sell their house, it has been on the market for two months.

• Correct

• Incorrect

So the quality of the print was not good, I changed the typewriter ribbon.

• Correct

• Incorrect

The lifeguard will warn you about the riptides, or she may require you to get out of the water.

• Correct

• Incorrect

You should have finished the work yesterday, yet is not close to being finished today.

• Correct

• Incorrect

The phone rang again and again, so the receptionist was not able to get much work done.

• Correct

• Incorrect

The missing wallet was found, but the cash and credit cards had been removed.

• Correct

• Incorrect

Or you can drive your car for another 2,000 miles, you can get it fixed.

• Incorrect

• Correct

The chemist was awarded the Nobel Prize, he flew to Europe to accept it.

• Correct

• Incorrect

The software should be used on a laptop computer, and this computer is a laptop.

• Correct

• Incorrect