【单选题】常用固体润滑剂有石墨、二硫化钼和( )等。
【单选题】宝洁公司和联合利华公司都是生产日用化工商品的企业是一对竞争对手从消费需求的角度来看他们属于()
【单选题】The first flying vertebrates were true reptiles in which one of the fingers of the front limbs became very elongated, providing support for a flap of stretched skin that served as a wing. These were t...
A.
Characteristics of pterosaur wings
B.
The discovery of fossil remains of Archaeopteryx
C.
Reasons for the extinction of early flying vertebrates
D.
The development of flight in reptiles and birds
【单选题】某病人服用药物的最低限量后即产生明显的药理效应或不良反应,是病人的( )反应。
【单选题】宝洁公司和联合公司利华公司都是生产日用化工产品的企业,是一对竞争对手,从消费需求的角度来看,它们属于( )
【单选题】The very first known settlers of Britain were _________ .
【单选题】What is known about the influenza virus?
A.
It was first found in a group of very old birds.
B.
All the different strains can be found in wild birds.
C.
It existed over 100 million years ago.
D.
It can survive in many different places.