B. We fixed the hole in the fence so the dog can't get out now.
There has to be a comma after fence.
Student drivers are required to keep a log of their supervised driving hours. However, not all students are diligent in their record-keeping.
The transition that should be used to combine these sentences is the following one: however. This adverb is used to introduce a statement that contrasts with or appears to contradict something that has been previously said. In this case, you are saying that student drivers should keep a written record of their supervised driving hours yet you are also stating that not all of them do it thoroughly and well.
Opinions are subjective, as they can vary from person to person but facts are objective.
Pejorative means to make worse.
Air is a homogeneous mixture.
Heterogeneous mixture means that the components are not evenly distributed, just like a mixture of sand and water where we can identify the individual components visually.
In the final paragraph he says serve the unknown
