—Right, just as many old people do in our city.
A:both; and
B:either; or
C:neither; nor
D:not only; but also
塑料矿泉水瓶遇热水会变____,又变凉后,矿泉水瓶会变____。
据报道,意大利科学家使用普通氧分子与带正电的氧离子作用,制造出新物质O4.下列关于O4的说法,正确的是( )