Ⅰ. be surprised 为“动词+形容词”结构，在句中作谓语，意为：“感到吃惊”. be surprised at 表“对……感到吃惊”
Ⅱ. in surprise为“介词+名词”结构。在句中作状语。意为：“吃惊地”。如：
① She was surprised. 她感到吃惊。
② Everybody was surprised at you. 大家都对你感到吃惊。
③ John turned round and looked at him in surprise. 约翰转过身去，吃惊地看着他。