Do you know Uncle Tom is crazy about gardening?-Sure. He his flowers in the garden

问题补充：

--- Do you know Uncle Tom is crazy about gardening?

---Sure. He his flowers in the garden now.

A. may be watering

B. must be watering

C. could look after

D. ought to watch

答案：

A. may be watering

(答案→)B. must be watering

C. could look after

D. ought to watch

解析：考情态动词表示猜测的用法。在表示十分肯定的猜测时，要用must。从对话来判断，此刻Uncle Tom一定正在花园里种花呢。选项A是干扰项，要注意may在表示猜测时，仅能表示不是十分有把握的猜测。