题目内容：
请在第__(47)__处填上正确答案。
A．Natural sponges become cleaning aids. B．We pollute the ocean when we use it as a garbage dump.
C．The area of the sea is becoming smaller anal smaller.
D．Along with salt, other minerals are left after evaporation.
E．We even use their bones for fertilizer.
F．Some of its contents may cause illness.
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