聚乙烯、聚氯乙烯、有机玻璃都是常见的塑料。塑料属于[ ]

A．金属材料

B．合成材料

C．复合材料

D．无机非金属材料

Which of the following is NOT right?

A．It was not until I reached London that I realized that my English was so poor.

B．Not until I reached London did I realize that my English was so poor.

C．I didn’t realize that my English was so poor until I reached London.

D．It was not until I reached London that did I realize that my English was so poor.