Answer:
√sentence contains errors
Explanation:
The given sentence actually contains errors. A closer look at the sentence, one will discover that the error occurred as a result of an omission of "comma" between "leaving" and "his".
Therefore, the corrected sentence is "Before leaving, his assistant finished typing the memo."
In the corrected sentence, I have inserted the omitted comma. Commas are used after introductory phrases, words and clauses that appear before the main clause.
