In the 1950s in the USA, most families had just one phone at home, and wireless phones _______ yet.
A:haven't invented
B:haven't been invented
C:hadn't invented
D:hadn't been invented
保护自然环境人人有责,下列哪一项是属于破坏环境的行为( )。
2000年某地超级杂交水稻的种植面积为20万公顷,2001年的种植面积比2000年增加25%,2001年超级杂交水稻的种植面积是多少万公顷?
请结合图1回答问题: