题目

One day, did not feeling well, Mr. Smith went to the hospital     1.____________ to have him examined. When he was given the test report,               2.____________ he was greatly shocked. “Am I dying?” He immediately                 3.____________ was felt very ill. Filled with sadness, he went back home,               4.____________ taking a lot of pills and even wrote his will. “Maybe                   5.____________ a doctor made a mistake”, Mr. Smith thought and                           6.___叶片是植物体进行光合作用的主要器官，它的表皮细胞外壁有一层透明而不能透水的结构是(    )A．角质层B．气孔C．保卫细胞D．叶脉