It rained heavily so we stay at home watching TV or surfing the Internet all day. A. cou

问题补充：

It rained heavily, so we stay at home watching TV or surfing the Internet all day.

A. could B. had to C. must

答案：

解析： 天气下着大雨，所以只能呆在家里看电视或上网，表示的客观的原因，have to表示客观的原因，意思为不得不，必须，故本题选B。