---We played football this afternoon.Why didn’t you play with us?

---Sorry, I really wanted to. But I __________Jim fix his bike then.

A．help

B．helped

C．am helping

D．was helping

下列哪些药物含有儿茶酚的结构( )。

A．特布他林

B．盐酸克仑特罗

C．异丙肾上腺素

D．去甲肾上腺素

E．盐酸麻黄碱