预应力梁预留孔道，预留孔道按制孔的方式可分为（）。
A.波纹管或薄钢板
B.预埋式制孔器
C.抽拔式制孔器
D.橡胶管
参考答案：B, C
I sincerely suggest that you try your best to finish this project，unless you don’t ________the complaints from all directions.
A．care about
B．set about
C．bring about
D．go about
现代家禽业的支柱有哪些？
