–Will you read me a story Mummy?OK. You have one if you go to bed as soon as possible.

问题补充：

–Will you read me a story, Mummy?

--OK. You have one if you go to bed as soon as possible.

A. might

B. must

C. could

D. shall

答案：

A. might

B. must

C. could

(答案→)D. shall

解析：考查情态动词的用法。Might可能，must一定，必须 could可能 shall用于第二第三人称可以表示命令，警告，允诺，威胁，法律规范。此处是允诺。意为，如果你尽快上床，我会给你读一个故事。这是对孩子做出的允诺。