单项选择题
A．They join the physics club. B．They ask for an extension of the deadline. C．They work on the assignment together. D．They choose an easier assignment.
A．There has been a lot of controversy over the use of flag. B．The best athletes can wear uniforms with the design of the flag. C．There are precise regulations and customs to be followed. D．Americans can print the flag on their cushions or handkerchiefs.
A．Its rapid growth is beneficial to the world. B．It can be seen as a model by the rest of the world. C．Its success can’t be explained by elementary economics. D．It will continue to surge forward.