One must accomplish two things when earning a PhD. First one must understand a particular subject thoroughly. Secondly, one must extensively in knowledge about that subject.
You can only be in a position to solve advanced engineering problems if you have PhD training in engineering. To be admitted as a doctoral student, one must hold a masters degree in the Engineering or related subject and pass a comprehensive entrance exam.
Mexico, officially the United Mexican States, is a federal constitutional republic in North America. Working may require a work visa, which is difficult to get if you just want to freelance for a short time. Most of the government funded universities on mayor cities (state capital) have short courses on history, gastronomy and cultural subjects, most of them are almost free.
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