to do 表示动作还没发生,将要发生.如:
The teaching building is to be built this autumn.
doing 表示的是现在正在进行的动作.如:
The teaching building is being built.
to do 表示动作还没发生,将要发生.如:
The teaching building is to be built this autumn.
doing 表示的是现在正在进行的动作.如:
The teaching building is being built.