Complete the spaceship captain's dramatic audio log by choosing the correct substitution word for each blank.

"The aliens may attempt to board the ship. If so, we must initiate the lockdown sequence immediately."

"Have they breached the outer hull yet? I believe not, but our sensors are severely damaged."

"We need to reroute power to the shields. Anyone who fails to do so will face a swift court-martial."

"I ordered the pilot to evade their lasers, and she did with surprising enthusiasm."

"If so, we must initiate the lockdown sequence immediately."

If so is a common C1 substitution phrase that replaces an entire affirmative conditional clause. Here, it stands for "If they attempt to board the ship."

"I believe not, but our sensors are severely damaged."

Not substitutes for the negative clause "that they have not breached the hull."

"Anyone who fails to do so will face a swift court-martial."

Do so is a formal way to substitute for a previously mentioned verb phrase—in this case, "reroute power to the shields."

"...and she did with surprising enthusiasm."

The auxiliary verb did is used here to stand in for the past tense verb phrase "evaded their lasers," avoiding unnecessary repetition.