对于工业企业生产用气设备,其燃烧器是依据( )来选择的。
A.用气设备类型 B.加热工艺要求C.燃气供给压力 D.以上三项的综合
参考答案:D
Tony is said________ to New York,and now he is studying medicine in a famous college in America.
A.have gone
B.to have gone
C.going
D.to go
香豆素结构中α-吡哺酮环引起的红外吸收在
A.酚羟基B.内酯环结构C.1745~1715cm-1D.甲氧基E.3600~3200cm-1