题目内容
（请给出正确答案）
A.since 1982
B.since the 1970s but only for large bottles
C.since the 1960s but not for liquids with gas in them
D.since companies like Coca Cola first tried them
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更多“Plastics of various kinds have…”相关的问题
Which of the following comparison is correct？
A．Thermal conductivity: metal ＜ plastics
B．Thermal expansion: metal ＞ plastics
C．Density: metal ＞ plastics
D．None of the above
______ is the most effective approach to making plastic more environmentally friendly.
A) Using biodegradable plastics
B) Using photodegradable plastics
C) Recycling plastics
D) Burning plastics for volume reduction and/or energy
______ of plastics, the machine works perfectly.
A．Being made
B．Having made
C．Made
D．To be made
