commas go where the sentence changes the subject but is still a sentence
The synonyms are different words with the same meaning so basically you have to know the meaning to identify the synonym ;)
Who's the author??? I couldn't find any PDF files with just the title.
Answer:
Aphids remove sap from the plant with their piercing-sucking mouthparts. Tomato plants can tolerate large numbers of aphids without suffering yield loss. However, severe infestations can cause leaves to curl and may stunt plants.
