【单选题】In heavily populated agricultural areas, ______ when crops fail.
A.
everybody takes to water sports
C.
a shortage of water will help
D.
more energy will be used
【单选题】某动物的皮肤由多层细胞的表皮和真皮构成,表皮内有大量单细胞粘液腺,皮肤与肌肉紧密连接,皮下组织极少。下列动物中最符合以上描述的是:()
【单选题】When there is an important job, who is asked to do it?
【单选题】由排列紧密的上皮细胞和少量的细胞间质组成的是( )
【多选题】如果对某个研究课题进行主题检索时,可选择的检索字段有哪些