We found it difficult _ there on time.[ ]
A. get
B. to get
C. getting
D. got
答案:B
硫酸奎宁片经氯仿提取,在冰醋酸中用高氯酸滴定的反应系数比为( )。
A.1:1B.1:2C.1:3D.1:4E.3:2
慢性支气管炎最典型的症状是
A.桶状胸B.长期、反复咳嗽、咳痰C.肺部啰音D.胸痛E.缩唇呼气