Each of the candidates choose a subject area; mechanical, electrical, or HVAC. Each of the candidates choose a subject area: mechanical, electrical, or HVAC.

is it ; or :​

the correct answer is:   [d]:   " espionage " .

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a. "to practice" is the best phrase to complete the sentence.

explanation:

during the summer, she likes to practice her soccer skills so that she is ready to play in the fall.

(note that : all the other options "the practicing of", "practice for" and "to do a practice on" are inappropriate as they make the sentence grammatically incorrect.)