The survey shows that urban students spend about twice ___ money the ones from rural areas do.
Li Ling was a diligent boy . He ____ go to school though it was raining hard .
The work ____ be finished in such a short time .
— ____ he open the door ? — Yes , please .
— Do you have to take care of your mother at home ? — Yes , I ____ .
— You ought to have called her yesterday . — Yes , I know I ____ .