Câu hỏi:

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer that best fits each of the numbered blanks.

While Morgan was running his businesses he was also working on inventions. In 1914 he patented a device that he (21) _____________ the Morgan safety hood and smoke protector. A patent is an official document that gives an inventor control over (22) _____________ may use their invention. The safety hood was an early gas mask. A gas mask allows people to breathe in (23) _____________ where there is a lot of smoke or dangerous chemicals in the air. In 1916 an explosion trapped some workers in a gas-filled tunnel under Lake Erie. Morgan attracted (24) _____________ attention when he used the safety hood to rescue some of the workers. In 1923 Morgan patented another safety invention. This was a T-shaped traffic signal. It (25) _____________ moving arms that told traffic when to stop and go. It was not the first traffic signal, but it controlled traffic better than many existing signals.

Morgan died on August 27,1963, in Cleveland. After his death several schools were named for him.

(From "Morgan, Garrett." Britannica Elementary Library - Encyclopaedia Britannica)

In 1914 he patented a device that he (21) _____________ the Morgan safety hood and smoke protector.