影响果树扦插与压条生根成活的因素有哪些?
参考答案:
①内部因素:种与品种;树龄、枝龄、枝条部位;营养物质;植物生长调节剂;维生素。
②外部因素:温度;湿度;光照。
No matter how frequently ______, the works of him still attract people all over the world. [ ]
A. performed
B. performing
C. to be performed
D. being performed
21世纪的国际竞争是多方面的,而且日趋激烈,但归根到底是( )。
A.综合国力的竞争B.经济实力的竞争C.科技实力的竞争D.人才的竞争