单项选择题
A．capable of using two languages B．both clever and confident C．aware of their own limitations and strengths D．independent of their parents
A．they have to watch out for possible attacks B．their brain hemispheres take turns to rest C．the two halves of their brain are differently structured D．they have to constantly keep an eye on their companions
A．the fact that we produce too much garbage B．the fact that we’ve ignored long-term effect of disposal problems C．the fact that the world is actually swimming in the garbage D．the fact that we spend a lot of money disposing the garbage