综采工作面的割煤方式有（）、（）两种方式。
参考答案：单向割煤；双向割煤
Canada's flag is ____________.[ ]
A. red and white
B. white
I'm not only growing older and taller, but also ____than before.[ ]
A. clever
B.cleverer
C.cleverest
D.the cleverest
