改革开放新的历史起点上，我国政治体制改革的主要任务是什么？
The reader learns that toxic chemicals get into our food________.
A. when plastic becomes small enough to enter our food chain
B. because other animals are being killed by plastic
C. because plastic does not biodegrade
D. from plastic bags from supermarkets
According to the passage，which animals appear most often on the cave wails？
A. Birds.
Bison.
C. Horses.
D. Wild cats.
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