运送氧气瓶时,必须保证气瓶不致沾染()等。
参考答案:油脂、沥青
This year’s National Day ____ in a practical way, which is reported in People’s Daily.
A.is to be observed
B.observe
C.observes
D.is to observe
绿原酸(C16H18O9)被誉为“第七类营养素”,它可以从栽种较广的杜仲中提取.下列有关绿原酸的说法错误的是( )
A.绿原酸含有33个原子
B.在一定条件下,可燃烧生成CO2和H2O
C.该绿原酸中C、H、O的原子个数比为16:18:9
D.绿原酸(C16H18O9)相对分子质量为354