英语虚拟语气填空

题目

英语虚拟语气填空
This medicine is effctive,but if you _______(have) a fever this evening,give me a call
我填的were to have 求判断正误与解析

答案

were to have 错!
虚拟应该填：
should have （有“万一”的意思）
...,but if you should have a fever this evening,give me a call.
但如果万一你今晚发烧,请给我电话.