Inventions Online Tests
Letter Box MCQ (Multiple Choice Questions) PDF Download
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The Letter box Multiple Choice Questions (MCQ Quiz) with Answers PDF (Letter Box MCQ PDF e-Book) download to practice Inventions Tests. Learn Inventions and Inventors Multiple Choice Questions and Answers (MCQs), Letter Box quiz answers PDF for online elementary school classes. The Letter Box MCQ App Download: Free learning app for water heaters, steam engine, striking clock, modern neuroscience test prep for virtual online school.
The MCQ: Letter-drop letter box was discovered by; "Letter Box" App Download (Free) with answers: Sir William kennedy Dickson; Sir John Barber; Sir Philip Downing; Sir Louis Pasteur; for online elementary school classes. Solve Inventions and Inventors Quiz Questions, download Google eBook (Free Sample) for school certificate.
Letter Box MCQs PDF: Questions Answers Download
The first letter-box was discovered by
- Sir Jack Kilby
- Sir Albert Potts
- Sir Hans von Ohain
- Alexander Fleming
Letter-drop letter box was discovered by
- Sir William kennedy Dickson
- Sir John Barber
- Sir Philip Downing
- Sir Louis Pasteur
In which one of the following year the first letter-box was patented by the U.S postal service?
- 1803
- 1833
- 1858
- 1847
Inventions Practice Tests
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