1．[2017·湘潭]It is very useful to read English aloud for half ________ hour every day.
A．a B．an C．the
2．[2017·益阳]I bought ________ useful dictionary yesterday. ________ dictionary is very cheap.
A．a; A B．a; The C．an; The
3．[2017·岳阳]—Ben, is physics your favorite subject?
—Yes, and it is ________ important one.
A．a B．the C．an
