问题
When operating with a negative suction head, which of the following types of pumps will require priming？
A.Reciprocating
B.Centrifugal
C.Rotary
D.Gear
请帮忙给出正确答案和分析，谢谢！
Fatal error: Uncaught [XSException] ../../../usr/local/xunsearch/sdk/php/lib/XS.php(2559): Connection refused(C#111, localhost:8384)
thrown in /usr/local/xunsearch/sdk/php/lib/XS.php on line 2559
