土地储备实行()管理。A、计划 B、年度 C、整体 D、分阶段

My son is very shy, but can you imagine ____ at the English party?   [ ]

A. him sing                  

B. his singing      

C. him to sing              

D. his to sing

血管介入技术是以_____、_____和_____三大技术为基础。

三相电压不对称为什么能影响感应式三相电能表的误差。