No one ______ be more generous; he has a heart of gold.

—How is the debate of your essay?—It ____ well, but I ____one of the key points.

—What do you think of John?—He’s a good boy, but he ______ be really stubborn at times.

Being examined twice a year, whether it is a car or a bus or a truck, it is the rule that every driver____ obey in this city.

—         you drive a car? —No, I can' t.