单选题 Mr. Walton's physical therapist recommended that he ______ the treatment until the swelling has gone down.
A. continue
B. continued
C. has continued
D. is continuing

【正确答案】 A

【答案解析】选项(A)continue是虚拟语气形式。在以recommend(建议)引导的that从句中，动词使用原形。选项(B)continued是一般过去式或过去分词形式。选项(C)has continued是现在完成式。选项(D)is continuing是现在进行式。