抑制磷酸二酯酶的活性（）
A.氨茶碱
B.舒喘灵
C.654-2
D.酮替芬
E.肾上腺皮质激素
参考答案：A
You needn’t write on __________ line. You can write on __________ line.
A．every; every
B．every; every other
C．every other; each other
D．every; each other
2. 
3. 
4. 