舒巴坦的化学结构为（）.

A．水溶液不稳定，易水解脱氨 

B．灼烧后产生硫化氢气体，使醋酸铅试纸呈黑色 

C．遇丙二酸及醋酐，加热后显红棕色 

D．加氢氧化钠液温热后即显紫色 

E．在碱性条件下，糖类能加速其溶液的水解

— When did you last see your first teacher?

— On ______Thursday last July, at ______celebration of her 30th year of teaching. [ ]

A. a; the

B. a; a

C. \; the

D. \; a