---has your grandma been like this?- Since last night.A. How oftenB. How longC. WhenD.

问题补充：

---has your grandma been like this? --- Since last night.

A. How often

B. How long

C. When

D. How soon

答案：

A. How often

(答案→)B. How long

C. When

D. How soon

解析：根据答语内容Since last night.表示的是很长一段时间，问句的特殊疑问词用how long，故选B