Question

Select the correct option to complete the given sentence.
____________ exercise is always fun.

• A. To doing
• B. Do
• C. Having done
• D. Doing

Answer 1

The correct option is D Doing

The gerund always has the same function as a noun (although it looks like a verb), here, doing exercise. It ends with "ing" and is the complement of the verb "to be", here, "is". Hence, Option D is correct. The rest of the options do not adhere to this rule, hence incorrect.