The work we are doing is quite difficult, so your support will certainly________.[ ]

A. make any difference  

B. make a difference

C. be very different  

D. be of some difference

关于宫颈癌的病因，下列哪项是错误的

A．早产、多产、多育
B．病毒感染
C．激素替代治疗
D．性生活紊乱
E．经济落后