关于肾上腺素和去甲肾上腺素的叙述，错误的是

A．两者在化学结构上都属于儿茶酚胺

B．肾上腺素可使心输量增加

C．小剂量肾上腺素可引起骨骼肌血管舒张

D．去甲肾上腺素可升高血压

E．去甲肾上腺素可使心率加快

________ is very difficult. [ ]

A. lesson five

B. The lesson fifth

C. Five lesson

D. The fifth lesson