Below are explanations for the two Subordinate Clause Samples:

Subordinate Clauses from The Heart of Darkness

As a change came over the waters, as the serenity became less brilliant but more profound, the old river in its broad reach rested unruffled at the decline of day, after it had performed ages of good service to the race that peopled its banks, spread out in the tranquil dignity of a waterway leading to the uttermost ends of the earth. We looked at the venerable stream not in the vivid flush of a short day that comes and departs for ever, but in the august light of abiding memories since nothing is easier for a man who has, as the phrase goes, 'followed the sea' with reverence and affection than to evoke the great spirit of the past upon the lower reaches of the Thames.

As the interactive exercise instructs, the first step is to highlight the Main Verb Phrases to determine the clauses for analysis:

As a change came over the waters, as the serenity became less brilliant but more profound, the old river in its broad reach rested unruffled at the decline of day, after it had performed ages of good service to the race that peopled its banks, spread out in the tranquil dignity of a waterway leading to the uttermost ends of the earth. We looked at the venerable stream not in the vivid flush of a short day that comes and departs for ever, but in the august light of abiding memories since nothing is easier for a man who has, as the phrase goes, 'followed the sea' with reverence and affection than to evoke the great spirit of the past upon the lower reaches of the Thames.

There appears to be four subordinate clauses in the passage:

1. AS A CHANGE CAME OVER THE WATERS: Adverbial Subordinate Clause - AS is the dependent marker (can be moved or deleted)
2. AS THE SERENITY BECAME LESS BRILLIANT: Adverbial Subordinate Clause - AS is the dependent marker (can be moved or deleted)
3. AFTER IT HAD PERFORMED AGES OF GOOD SERVICE: Adverbial Subordinate Clause - AFTER is the dependent marker (can be moved or deleted)
4. SINCE NOTHING IS EASIER: Adverbial Subordinate Clause - SINCE is dependent marker (can be moved or deleted)

Challenge Sample

Margot’s mind reeled. Since she could hear the listless, scraping sounds of fingertips against the door, it haunted her to consider the sea of faces outside. They were faces she once knew in a different light, but now they were putrid reflections of squalor and decay. There was nothing left for her to glean from their lifeless eyes except the grim reminder that she was alone. She tried to ignore what she thought she saw, even though she was the last bastion of humanity. Death awaited her outside.

Again, the first step is to highlight the Main Verb Phrases to determine the clauses for analysis:

Margot’s mind reeled. Since she could hear the listless, scraping sounds of fingertips against the door, it haunted her to consider the sea of faces outside. They were faces she once knew in a different light, but now they were putrid reflections of squalor and decay. There was nothing left for her to glean from their lifeless eyes except the grim reminder that she was alone. She tried to ignore what she thought she saw, even though she was the last bastion of humanity. And only death awaited her outside.

For this sample, there appears to be two subordinate clauses in the passage:

1. SINCE SHE COULD HEAR THE LISTLESS, SCRAPING SOUNDS: Adverbial Subordinate Clause - SINCE is the dependent marker (can be moved or deleted)
2. EVEN THOUGH SHE WAS THE LAST BASTION OF HUMANITY: Adverbial Subordinate Clause - EVEN THOUGH is the dependent marker (can be moved or deleted)

Tips to Keep in Mind

The KEY MARKER for identifying Subordinate Clauses is the subordinator that precedes the subject of the clause.