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
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According to the passage,which animals appear most often on the cave wails?
A. Birds.
Bison.
C. Horses.
D. Wild cats.
How does the writer feel about sounds in general? 查看材料
A. They make him feel at home.
B. He thinks they should be ignored.
C. He believes they are part of our lives.
D. He prefers silence to loud noises.
谐波制动的变压器纵联差动保护中,设置差动速断元件的主要原因是()。
A. 为了提高差动保护的动作速度;
B. 为了防止在区内故障,较高的短路水平时,由于电流互感器的饱和产生高次谐波量增加,导致差动元件拒动;
C. 保护设置的双重化,互为备用;
D. 差动保护的后备保护。