下列物质，哪种不能由乙烯直接合成（）。
A、乙酸；
B、乙醇；
C、乙醛；
D、合成塑料。
参考答案：D
一青年人，肺门淋巴结肿大，PPD试验5U，硬结直径15mm，伴水泡，诊断为
A．结核病B．结节病C．淋巴瘤D．肺癌E．矽肺
---- What do you think of zoology?
---- In my opinion, zoology is ______ botany.
A．a subject so interesting as
B．as a interesting subject as
C．as interesting a subject as
D．interesting as a subject as
