求翻译：房地产开发（贰级，有效期至2011年10月28 日止），建筑材料批发兼零售。（上述经营范围涉及行政许可的项目凭有效许可证件经营）是什么意思？

Real estate development (Class-B, valid until October 28, 2011 only), building materials wholesale and retail. (The operating range of projects involving administrative licensing business with a valid license)

Real Estate Development (grade, which is valid until October 28, 2011 ) ended, building materials wholesale and retail. (The above scope of business projects involving administrative permission with valid operating permit)

The property development (two levels, stops term of validity to October 28, 2011), the building material wholesales the concurrently retail sales.(The above management scope involves project which administration permitted to depend on effective permission credential management)

Real estate development (second level, is valid until October 28, 2011), wholesale and retail of building materials. (Above business covering administrative licensing items with a valid operating license)