食管第3狭窄处()。
A.环咽肌收缩而成
B.由主动脉弓压迫食管所致
C.由左主支气管压迫食管所致
D.由右主支气管压迫食管所致
E.食管穿过横膈裂孔所致
参考答案:C
HIV主要感染下列哪种细胞()
A.CD4+T淋巴细胞
B.B淋巴细胞
C.单核细胞
D.神经胶质细胞
E.直肠黏膜上皮细胞
--- Did you return the book you borrowed from Tom?
--- Yes, I gave it to him ______ I saw him.
A.for the moment
B.the moment
C.for a moment
D.at the moment