Don’t have horse too fast it will get tired soon.A. ranB. to runC. runsD. running

问题补充：

Don’t have horse too fast, it will get tired soon.

A. ran

B. to run

C. runs

D. running

答案：

A. ran

B. to run

C. runs

(答案→)D. running

解析：have sb./sth. doing sth.让一直做某事，或者让某物一直处于某种状态。