adj.谨慎的；提防的
动词guard的过去式和过去分词形式.
He wrote of his failing health in guarded terms. 他用谨慎的字句提到了他的越来越坏的健康。
He was friendly but guarded, especially toward Arthur. 他态度友好，但有戒心，特别是对阿瑟。
