已知函数$f\left(x\right)=\left\{\begin{array}{c}x,x\ge 0\\ 2^x,x<0\end{array}\right.$，则ff(-1)（    ）

watch    learn     be    have      Chinese    
    Dick and Ellen come from America. Now they ____  in Tianjin. Every morning they get up very early. Then they go to work by car. They start their work at 8:30. They are very busy. They ____  lunch at 12:30. After lunch they work again. They finish their work at 5:30 p.m. In the evening Dick takes Chinese lessons because he wants ____  Chinese. Ellen stays at home and ____ TV. They like to talk with Chinese people. They often say "Chinese people are very friendly". They like to stay in ____  and they like to work with Chinese people.

下列物质的电子式书写正确的是（　　）