Direction: The following sentence test your ability to recognize grammar and usage errors. Each sentence contains either a single error or nor error at all. No sentence contains more than one error. The error, if there is one, is underlined and lettered. If the sentence contains an error, select the one underlined part that must be changed to make the sentence correct. If the sentence is correct, select choice. In choosing answers, follow the requirements of standard written English.

Sir James Dewar (A) invented the thermos (B) to keep heat away from the liquefied gas (C) with which he was (D) experiment. (E) No error