A-A+
A．They are necessary for modern man.B．They are
问题详情
A．They are necessary for modern man.
B．They are unnecessary for survival.
C．They are as good as computers.
D．They are dangerous for us.
参考答案
正确答案：B
解析：文中说"Jet planes and computer are fine"，但马上转而说“but not necessafy for survival”，说明“飞机与计算机虽好，但对生存来说不需要”，故选B。
