The second theme is that the author want his readers to know that there is more to life then we can see, or that a building/ strengthening a friendship is worth more than any treasure
An independent clause stands alone. That's your answer :)
I strongly believe that time spent learning a trade for career development is as valuable as the time invested in a college degree.
I think that the most important thing is the time invested in your dreams, it doesn't matter if it is a college degree or a trade, nor if one takes longer than the other or if one of them will get you more money. Time spent in something you don't like to do, eventually, will be a waste because you will not be happy doing that job and will probably quit sooner or later.
Whether you pick one thing or the other, you must really love it, you have to be passionate about it and, if you do this, it'll be never a waste of time.
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“Ah, Are You Digging on My Grave?” by Thomas Hardy is a story about a woman that is dead and she suddenly discover someone digging in her grave, Hardy use irony to disappoint the speaker’s expectation because she see that is her dog who is there and thought that he is doing that because he missed her, however the dog simply replies that was just burying a bone in case he was hungry later. The answer is It uses irony to show the woman that she is deeply missed.