Final answer:
The sentences acknowledging limitations to recycling and reusability serve as counterarguments in the recycling debate.
Step-by-step explanation:
The two sentences in the passage that introduce counterarguments to the speaker's position in favor of recycling are: "Admittedly, we cannot reuse or recycle all of the materials we use in our daily lives." and "Some materials are not recyclable, such as certain food containers. Others items are not biodegradable regardless of what we reuse them for, and that can create problems in the long run." These sentences acknowledge that there are limitations to recycling and reusing, which an opponent of the speaker's position could use to argue against the effectiveness of recycling.