题目选项分析

Researchers agreed that the study of new treatments for heart attack patients was extremely important but that more research was needed to determine whether balloon angioplasty preceded by ultrasound is any better for heart attack patients than the balloon procedure by itself.

Researchers agreed that the study of new treatments for heart attack patients was extremely important but more research was needed for determining whether or not balloon angioplasty preceded by ultrasound is any better for heart attack patients than is the balloon procedure by itself.