Everyone who `underline("finished")` writing can go home.

It began to rain heavily just when underline("I prepare") to go out.

Select the most appropriate option to substitute the underlined segment in the given sentence. If no substitution is required, select No improvement. Long after those five horses finish drinking water from the trough, an old horse appeared over the brow of the hill. (a) had finished (b) have finished (c) no improvement (d) had been finishing